D Wiki - User contributions [en-gb]

http://d2.reldb.org/api.php?action=feedcontributions&feedformat=atom&user=Dave D Wiki - User contributions [en-gb] 2026-05-06T14:10:49Z User contributions MediaWiki 1.26.2 http://d2.reldb.org/index.php?title=Main_Page&diff=159 Main Page 2018-08-07T09:10:51Z

<p>Dave: </p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's ''The Third Manifesto''], and were produced and curated by participants of the TTM mailing list.<br /> <br /> New visitors could start here with some<br /> * [[RecommendedReading]].<br /> * [[TheThirdManifesto]]<br /> * [[ThirdManifestoParaphrase]]<br /> <br /> Other articles hosted here:<br /> <br /> * [[Catalog]]<br /> * [[Update through views: a possible approach]]<br /> * [[Update through views: a seminal paper - appreciation, commentary, critique]]<br /> * [[Update through views: a not-quite-so seminal paper - asking too much; can base relations be orthogonal?]]<br /> * [[PhilipTutorial|"Philip's Tutorial"]]<br /> <br /> Consult the [//meta.wikimedia.org/wiki/Help:Contents User's Guide] for general information on using this wiki software.</div>

Dave http://d2.reldb.org/index.php?title=Main_Page&diff=158 Main Page 2018-08-07T09:10:29Z

<p>Dave: </p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's ''The Third Manifesto''], and were produced and curated by participants of the TTM mailing list.<br /> <br /> New visitors could start here with some<br /> * [[RecommendedReading]].<br /> * [[TheThirdManifesto]]<br /> * [[ThirdManifestoParaphrase]]<br /> <br /> Other articles hosted here:<br /> <br /> * [[Catalog]]<br /> * [[Update through views: a possible approach]]<br /> * [[Update through views: a seminal paper - appreciation, commentary, critique]]<br /> * [[Update through views: a not-quite-so seminal paper - asking too much; can base relations be orthogonal?]]<br /> * [[PhilipTutorial]]<br /> <br /> Consult the [//meta.wikimedia.org/wiki/Help:Contents User's Guide] for general information on using this wiki software.</div>

Dave http://d2.reldb.org/index.php?title=Main_Page&diff=157 Main Page 2018-08-07T09:09:41Z

<p>Dave: </p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's ''The Third Manifesto''], and were produced and curated by participants of the TTM mailing list.<br /> <br /> New visitors could start here with some<br /> * [[RecommendedReading]].<br /> * [[TheThirdManifesto]]<br /> * [[ThirdManifestoParaphrase]]<br /> <br /> Other articles hosted here:<br /> <br /> * [[Catalog]]<br /> * [[Update through views: a possible approach]]<br /> * [[Update through views: a seminal paper - appreciation, commentary, critique]]<br /> * [[Update through views: a not-quite-so seminal paper - asking too much; can base relations be orthogonal?]]<br /> * [[Philip's Tutorial|PhilipTutorial]]<br /> <br /> Consult the [//meta.wikimedia.org/wiki/Help:Contents User's Guide] for general information on using this wiki software.</div>

Dave http://d2.reldb.org/index.php?title=Update_through_views:_a_seminal_paper_-_appreciation,_commentary,_critique&diff=130 Update through views: a seminal paper - appreciation, commentary, critique 2017-02-09T13:02:07Z

<p>Dave: Now with 100% more correct syntax for external link.</p> <hr /> <div>My gold standard for expressing principles to do with updating-through-views is Dayal & Bernstein 1978 "On the Updatability of Relational Views", section "Correctness Criteria for View Updates". That's not to say I entirely agree with them, but I'm impressed that they have expressed their approach in one sentence of ~50 words, plus 4 paragraphs to explain each key term. The surprise is how soon this was published after Codd's papers elaborating the RM.<br /> <br /> Contrast that [http://computing.derby.ac.uk/c/codds-twelve-rules/ Codd's 12 Rules], including the prescription for update-through-view, and definition for "theoretically updatable" was published in 1985. Codd says "Although I have defined each rule in earlier papers, I believe this to be the first occurrence of all twelve of them together.", and cites a paper "conceived in 1981".<br /> <br /> Another influential paper of the same vintage, Bancilhon & Spyratos 1981, introduced the "constant complement" approach (which anticipates Date's Principle of Interchangeability).<br /> <br /> == Correctness Criteria for View Updates ==<br /> <br /> The model sentence:<br /> <blockquote><br /> Given a semantically consistent schema extension '''$*''', we say that an update operation '''u''' on view extension '''V*''' is ''translatable'' if there is a ''unique'' set of updates '''U''' on '''$*''' producing the desired update on '''V*''', such that there are ''no extraneous updates'' in '''U''', ''no side effects'' on '''V*''', and '''U''' ''preserves semantic consistency''.<br /> </blockquote><br /> Explanations:<br /> <blockquote><br /> An update is ''extraneous'' in '''U''' if '''U''' produces the same effect on the view extension with or without the extraneous update.<br /> </blockquote><br /> <blockquote><br /> The set of updates '''U''' has ''no side effects'' if ''only'' the desired update is performed on the view. <br /> </blockquote><br /> <blockquote><br /> A set of update operations on a semantically consistent schema extension ''preserves semantic consistency'' if the resulting schema extension is also semantically consistent.<br /> </blockquote><br /> <blockquote><br /> The ''uniqueness'' criterion is controversial and requires some justification. This criterion says that the inverse mapping (of the view definition) from view extensions to schema extensions must be a function. <br /> </blockquote><br /> <br /> They add:<br /> <blockquote><br /> There is another uncomfortable dimension to the issue of translatability. In our examples, we translated a view insertion only into ''insertions'' on the base relations. Should we permit an insertion to map to deletions and replacements as well? <br /> </blockquote><br /> <br /> Their conclusion I find elusive (and it appears only at the end of the abstract, rather than in the Conclusion section):<br /> <blockquote><br /> In summary, our theorems show that there are very few situations in which view updates are possible--even fewer, in fact, than intuition might suggest. <br /> </blockquote><br /> How few are "very few"? Compared to what? How few "might intuition suggest"? Was the prevailing opinion at the time that all or nearly all updates through views were possible?<br /> <br /> == Commentary, Critique ==<br /> <br /> Taking the requirements in sequence presented.<br /> <br /> === ''no extraneous updates'' ===<br /> <br /> In other words (and to put it positively), each "update" in '''U''' must be necessary to achieving the required effect on the extension. (But this doesn't say what an "update" is. Presumably any tuple inserted, deleted or replaced. The only example given is a tuple insert into base where a value is to be concocted for an attribute projected out of the view. D&B regard such a value as arbitrary, because any other valid value would do as well. Curiously, they instead propose inserting NULL -- as if that's not arbitrary!) So both tuples and attribute values can be ''extraneous''.<br /> <br /> === ''no side effects'' ===<br /> <br /> That is, the effect on the view must be exactly what was requested in the update. This is "no side effects" in the sense "A secondary, typically undesirable effect" [Oxford online dictionary]. This would be an uncontroversial criterion were it not that Date & McGoveran's 1994 treatment did not require it. (And Date had to correct that by giving a grand title "Assignment Principle".)<br /> <br /> === ''preserves semantic consistency'' ===<br /> <br /> I.e. all constraints must hold; Date's "Golden Rule". Again uncontroversial. D&B consider only key/Functional Dependencies, not Foreign Key constraints/INclusion Dependencies, nor more exotic constraints. "Since keys are syntactic constructs, they will give us a compile-time check on update translatabililty." [Section 5.] And their detailed workings do not take any opportunity to consider at run-time the content of the base relations.<br /> <br /> === ''uniqueness'' ===<br /> <br /> D&B admit up front this is controversial. The three sentences immediately following the explanation above:<br /> <blockquote><br /> The alternative, of course, is that there are several distinct sets of schema updates that will alter the view extension as desired. The problem in the latter case is how to choose which set to apply. An arbitrary choice seems unacceptable. <br /> </blockquote><br /> I agree "an arbitrary choice seems unacceptable" -- this is the same thinking as rejecting ''extraneous'' updates.<br /> <br /> As to "how to choose", I think D&B have simply made an error in logic (their "of course" does not follow). For there to be a unique such "set of schema updates", yes it would be sufficient for there to be an inverse mapping from view to schema (base) -- that's an ideal; but it is <u>not necessary</u>. To be ''unique'', all that's needed is there be one set of non-''extraneous'' schema updates that wil alter the view extension as desired. That is, one set that alters the view extension as desired <u>for this particular update request</u> (delete, insert, etc). The inverse mapping criterion amounts to not only achieving this particular request, but also being able to reverse that request, returning both the view and base to ''status quo ante''.<br /> <br /> === map ''insertions only into insertions'' ===<br /> <br /> From later in the explanation:<br /> <blockquote><br /> Some additional semantics are required. We have chosen to map view updates of one type (insertions, deletions, replacements) to schema updates ''of the same type''. Theoretically, this choice is arbitrary. Intuitively, though, it makes good sense ...<br /> </blockquote><br /> <br /> I cannot see it makes sense in all cases: the only way to ensure insert-through-MINUS is to insert into the minuend, but <u>delete</u> from the subtrahend -- otherwise the insertion will not appear in the result, i.e. a ''side effect''.<br /> <br /> The examples D&B consider here (such as replacing a tuple for a requested insert, in order to preserve semantic consistency) all fail on other of their criteria -- especially causing ''side effects'', or risking causing ''side effects'' depending on other content of the base schema.<br /> <br /> Furthermore since they're concluding "there are very few situations in which view updates are possible", there is no requirement for "some additional semantics". 'Back off' the semantic requirements, and more views will be updatable-through.<br /> <br /> == The paper's contribution to [[Update through views: a possible approach]] ==<br /> <br /> The ''preserves semantic consistency'' ("Golden Rule") and ''no side effects'' ("Assignment Principle") are my prescription 1 and 2.<br /> <br /> D&B's aim for "compile time check on update translatability" is another implicit criterion/restraint on algorithms. It appears as my prescription 3.<br /> <br /> ''no extraneous updates'' and ''unique'' set of updates are my prescription 4 (necessary and sufficient/''essential'' tuples and attribute values) -- which is more explicit about what constitutes a "set of updates" and what it is for something in that set to be ''extraneous''.<br /> <br /> Can I express the prescriptions as succinctly as D&B's criteria?<br /> <br /> Given a semantically consistent schema extension '''$*''', we say that an update operation '''u''' on view extension '''V*''' is ''translatable'' if there is a set of tuple inserts, deletes and replacements '''U''' on '''$*''', together ''sufficient'' to produce the desired update on '''V*''', such that each tuple operation is ''necessary'' in '''U''', the ''precise effect'' on '''V*''' is as requested, '''U''' ''preserves semantic consistency'', and the ''translation is statically determinable'' purely from the form of the update request, the schema and view definition and the semantic integrity constraints.<br /> <br /> == References ==<br /> <br /> Dayal and Bernstein 1978 "On the Updatability of Relational Views”<br /> https://pdfs.semanticscholar.org/39f4/853a35a913c714c5f3956dbefd02916447c4.pdf<br /> <br /> See also [[Update through views: a possible approach#References]]</div>

Dave http://d2.reldb.org/index.php?title=Update_through_views:_a_seminal_paper_-_appreciation,_commentary,_critique&diff=129 Update through views: a seminal paper - appreciation, commentary, critique 2017-02-09T13:00:58Z

<p>Dave: Fix link syntax</p> <hr /> <div>My gold standard for expressing principles to do with updating-through-views is Dayal & Bernstein 1978 "On the Updatability of Relational Views", section "Correctness Criteria for View Updates". That's not to say I entirely agree with them, but I'm impressed that they have expressed their approach in one sentence of ~50 words, plus 4 paragraphs to explain each key term. The surprise is how soon this was published after Codd's papers elaborating the RM.<br /> <br /> Contrast that [[Codd's 12 Rules http://computing.derby.ac.uk/c/codds-twelve-rules/]], including the prescription for update-through-view, and definition for "theoretically updatable" was published in 1985. Codd says "Although I have defined each rule in earlier papers, I believe this to be the first occurrence of all twelve of them together.", and cites a paper "conceived in 1981".<br /> <br /> Another influential paper of the same vintage, Bancilhon & Spyratos 1981, introduced the "constant complement" approach (which anticipates Date's Principle of Interchangeability).<br /> <br /> == Correctness Criteria for View Updates ==<br /> <br /> The model sentence:<br /> <blockquote><br /> Given a semantically consistent schema extension '''$*''', we say that an update operation '''u''' on view extension '''V*''' is ''translatable'' if there is a ''unique'' set of updates '''U''' on '''$*''' producing the desired update on '''V*''', such that there are ''no extraneous updates'' in '''U''', ''no side effects'' on '''V*''', and '''U''' ''preserves semantic consistency''.<br /> </blockquote><br /> Explanations:<br /> <blockquote><br /> An update is ''extraneous'' in '''U''' if '''U''' produces the same effect on the view extension with or without the extraneous update.<br /> </blockquote><br /> <blockquote><br /> The set of updates '''U''' has ''no side effects'' if ''only'' the desired update is performed on the view. <br /> </blockquote><br /> <blockquote><br /> A set of update operations on a semantically consistent schema extension ''preserves semantic consistency'' if the resulting schema extension is also semantically consistent.<br /> </blockquote><br /> <blockquote><br /> The ''uniqueness'' criterion is controversial and requires some justification. This criterion says that the inverse mapping (of the view definition) from view extensions to schema extensions must be a function. <br /> </blockquote><br /> <br /> They add:<br /> <blockquote><br /> There is another uncomfortable dimension to the issue of translatability. In our examples, we translated a view insertion only into ''insertions'' on the base relations. Should we permit an insertion to map to deletions and replacements as well? <br /> </blockquote><br /> <br /> Their conclusion I find elusive (and it appears only at the end of the abstract, rather than in the Conclusion section):<br /> <blockquote><br /> In summary, our theorems show that there are very few situations in which view updates are possible--even fewer, in fact, than intuition might suggest. <br /> </blockquote><br /> How few are "very few"? Compared to what? How few "might intuition suggest"? Was the prevailing opinion at the time that all or nearly all updates through views were possible?<br /> <br /> == Commentary, Critique ==<br /> <br /> Taking the requirements in sequence presented.<br /> <br /> === ''no extraneous updates'' ===<br /> <br /> In other words (and to put it positively), each "update" in '''U''' must be necessary to achieving the required effect on the extension. (But this doesn't say what an "update" is. Presumably any tuple inserted, deleted or replaced. The only example given is a tuple insert into base where a value is to be concocted for an attribute projected out of the view. D&B regard such a value as arbitrary, because any other valid value would do as well. Curiously, they instead propose inserting NULL -- as if that's not arbitrary!) So both tuples and attribute values can be ''extraneous''.<br /> <br /> === ''no side effects'' ===<br /> <br /> That is, the effect on the view must be exactly what was requested in the update. This is "no side effects" in the sense "A secondary, typically undesirable effect" [Oxford online dictionary]. This would be an uncontroversial criterion were it not that Date & McGoveran's 1994 treatment did not require it. (And Date had to correct that by giving a grand title "Assignment Principle".)<br /> <br /> === ''preserves semantic consistency'' ===<br /> <br /> I.e. all constraints must hold; Date's "Golden Rule". Again uncontroversial. D&B consider only key/Functional Dependencies, not Foreign Key constraints/INclusion Dependencies, nor more exotic constraints. "Since keys are syntactic constructs, they will give us a compile-time check on update translatabililty." [Section 5.] And their detailed workings do not take any opportunity to consider at run-time the content of the base relations.<br /> <br /> === ''uniqueness'' ===<br /> <br /> D&B admit up front this is controversial. The three sentences immediately following the explanation above:<br /> <blockquote><br /> The alternative, of course, is that there are several distinct sets of schema updates that will alter the view extension as desired. The problem in the latter case is how to choose which set to apply. An arbitrary choice seems unacceptable. <br /> </blockquote><br /> I agree "an arbitrary choice seems unacceptable" -- this is the same thinking as rejecting ''extraneous'' updates.<br /> <br /> As to "how to choose", I think D&B have simply made an error in logic (their "of course" does not follow). For there to be a unique such "set of schema updates", yes it would be sufficient for there to be an inverse mapping from view to schema (base) -- that's an ideal; but it is <u>not necessary</u>. To be ''unique'', all that's needed is there be one set of non-''extraneous'' schema updates that wil alter the view extension as desired. That is, one set that alters the view extension as desired <u>for this particular update request</u> (delete, insert, etc). The inverse mapping criterion amounts to not only achieving this particular request, but also being able to reverse that request, returning both the view and base to ''status quo ante''.<br /> <br /> === map ''insertions only into insertions'' ===<br /> <br /> From later in the explanation:<br /> <blockquote><br /> Some additional semantics are required. We have chosen to map view updates of one type (insertions, deletions, replacements) to schema updates ''of the same type''. Theoretically, this choice is arbitrary. Intuitively, though, it makes good sense ...<br /> </blockquote><br /> <br /> I cannot see it makes sense in all cases: the only way to ensure insert-through-MINUS is to insert into the minuend, but <u>delete</u> from the subtrahend -- otherwise the insertion will not appear in the result, i.e. a ''side effect''.<br /> <br /> The examples D&B consider here (such as replacing a tuple for a requested insert, in order to preserve semantic consistency) all fail on other of their criteria -- especially causing ''side effects'', or risking causing ''side effects'' depending on other content of the base schema.<br /> <br /> Furthermore since they're concluding "there are very few situations in which view updates are possible", there is no requirement for "some additional semantics". 'Back off' the semantic requirements, and more views will be updatable-through.<br /> <br /> == The paper's contribution to [[Update through views: a possible approach]] ==<br /> <br /> The ''preserves semantic consistency'' ("Golden Rule") and ''no side effects'' ("Assignment Principle") are my prescription 1 and 2.<br /> <br /> D&B's aim for "compile time check on update translatability" is another implicit criterion/restraint on algorithms. It appears as my prescription 3.<br /> <br /> ''no extraneous updates'' and ''unique'' set of updates are my prescription 4 (necessary and sufficient/''essential'' tuples and attribute values) -- which is more explicit about what constitutes a "set of updates" and what it is for something in that set to be ''extraneous''.<br /> <br /> Can I express the prescriptions as succinctly as D&B's criteria?<br /> <br /> Given a semantically consistent schema extension '''$*''', we say that an update operation '''u''' on view extension '''V*''' is ''translatable'' if there is a set of tuple inserts, deletes and replacements '''U''' on '''$*''', together ''sufficient'' to produce the desired update on '''V*''', such that each tuple operation is ''necessary'' in '''U''', the ''precise effect'' on '''V*''' is as requested, '''U''' ''preserves semantic consistency'', and the ''translation is statically determinable'' purely from the form of the update request, the schema and view definition and the semantic integrity constraints.<br /> <br /> == References ==<br /> <br /> Dayal and Bernstein 1978 "On the Updatability of Relational Views”<br /> https://pdfs.semanticscholar.org/39f4/853a35a913c714c5f3956dbefd02916447c4.pdf<br /> <br /> See also [[Update through views: a possible approach#References]]</div>

Dave http://d2.reldb.org/index.php?title=Update_through_views:_a_seminal_paper_-_appreciation,_commentary,_critique&diff=128 Update through views: a seminal paper - appreciation, commentary, critique 2017-02-09T13:00:35Z

<p>Dave: Added link to Codd's 12 Rules</p> <hr /> <div>My gold standard for expressing principles to do with updating-through-views is Dayal & Bernstein 1978 "On the Updatability of Relational Views", section "Correctness Criteria for View Updates". That's not to say I entirely agree with them, but I'm impressed that they have expressed their approach in one sentence of ~50 words, plus 4 paragraphs to explain each key term. The surprise is how soon this was published after Codd's papers elaborating the RM.<br /> <br /> Contrast that [[Codd's 12 Rules,http://computing.derby.ac.uk/c/codds-twelve-rules/]], including the prescription for update-through-view, and definition for "theoretically updatable" was published in 1985. Codd says "Although I have defined each rule in earlier papers, I believe this to be the first occurrence of all twelve of them together.", and cites a paper "conceived in 1981".<br /> <br /> Another influential paper of the same vintage, Bancilhon & Spyratos 1981, introduced the "constant complement" approach (which anticipates Date's Principle of Interchangeability).<br /> <br /> == Correctness Criteria for View Updates ==<br /> <br /> The model sentence:<br /> <blockquote><br /> Given a semantically consistent schema extension '''$*''', we say that an update operation '''u''' on view extension '''V*''' is ''translatable'' if there is a ''unique'' set of updates '''U''' on '''$*''' producing the desired update on '''V*''', such that there are ''no extraneous updates'' in '''U''', ''no side effects'' on '''V*''', and '''U''' ''preserves semantic consistency''.<br /> </blockquote><br /> Explanations:<br /> <blockquote><br /> An update is ''extraneous'' in '''U''' if '''U''' produces the same effect on the view extension with or without the extraneous update.<br /> </blockquote><br /> <blockquote><br /> The set of updates '''U''' has ''no side effects'' if ''only'' the desired update is performed on the view. <br /> </blockquote><br /> <blockquote><br /> A set of update operations on a semantically consistent schema extension ''preserves semantic consistency'' if the resulting schema extension is also semantically consistent.<br /> </blockquote><br /> <blockquote><br /> The ''uniqueness'' criterion is controversial and requires some justification. This criterion says that the inverse mapping (of the view definition) from view extensions to schema extensions must be a function. <br /> </blockquote><br /> <br /> They add:<br /> <blockquote><br /> There is another uncomfortable dimension to the issue of translatability. In our examples, we translated a view insertion only into ''insertions'' on the base relations. Should we permit an insertion to map to deletions and replacements as well? <br /> </blockquote><br /> <br /> Their conclusion I find elusive (and it appears only at the end of the abstract, rather than in the Conclusion section):<br /> <blockquote><br /> In summary, our theorems show that there are very few situations in which view updates are possible--even fewer, in fact, than intuition might suggest. <br /> </blockquote><br /> How few are "very few"? Compared to what? How few "might intuition suggest"? Was the prevailing opinion at the time that all or nearly all updates through views were possible?<br /> <br /> == Commentary, Critique ==<br /> <br /> Taking the requirements in sequence presented.<br /> <br /> === ''no extraneous updates'' ===<br /> <br /> In other words (and to put it positively), each "update" in '''U''' must be necessary to achieving the required effect on the extension. (But this doesn't say what an "update" is. Presumably any tuple inserted, deleted or replaced. The only example given is a tuple insert into base where a value is to be concocted for an attribute projected out of the view. D&B regard such a value as arbitrary, because any other valid value would do as well. Curiously, they instead propose inserting NULL -- as if that's not arbitrary!) So both tuples and attribute values can be ''extraneous''.<br /> <br /> === ''no side effects'' ===<br /> <br /> That is, the effect on the view must be exactly what was requested in the update. This is "no side effects" in the sense "A secondary, typically undesirable effect" [Oxford online dictionary]. This would be an uncontroversial criterion were it not that Date & McGoveran's 1994 treatment did not require it. (And Date had to correct that by giving a grand title "Assignment Principle".)<br /> <br /> === ''preserves semantic consistency'' ===<br /> <br /> I.e. all constraints must hold; Date's "Golden Rule". Again uncontroversial. D&B consider only key/Functional Dependencies, not Foreign Key constraints/INclusion Dependencies, nor more exotic constraints. "Since keys are syntactic constructs, they will give us a compile-time check on update translatabililty." [Section 5.] And their detailed workings do not take any opportunity to consider at run-time the content of the base relations.<br /> <br /> === ''uniqueness'' ===<br /> <br /> D&B admit up front this is controversial. The three sentences immediately following the explanation above:<br /> <blockquote><br /> The alternative, of course, is that there are several distinct sets of schema updates that will alter the view extension as desired. The problem in the latter case is how to choose which set to apply. An arbitrary choice seems unacceptable. <br /> </blockquote><br /> I agree "an arbitrary choice seems unacceptable" -- this is the same thinking as rejecting ''extraneous'' updates.<br /> <br /> As to "how to choose", I think D&B have simply made an error in logic (their "of course" does not follow). For there to be a unique such "set of schema updates", yes it would be sufficient for there to be an inverse mapping from view to schema (base) -- that's an ideal; but it is <u>not necessary</u>. To be ''unique'', all that's needed is there be one set of non-''extraneous'' schema updates that wil alter the view extension as desired. That is, one set that alters the view extension as desired <u>for this particular update request</u> (delete, insert, etc). The inverse mapping criterion amounts to not only achieving this particular request, but also being able to reverse that request, returning both the view and base to ''status quo ante''.<br /> <br /> === map ''insertions only into insertions'' ===<br /> <br /> From later in the explanation:<br /> <blockquote><br /> Some additional semantics are required. We have chosen to map view updates of one type (insertions, deletions, replacements) to schema updates ''of the same type''. Theoretically, this choice is arbitrary. Intuitively, though, it makes good sense ...<br /> </blockquote><br /> <br /> I cannot see it makes sense in all cases: the only way to ensure insert-through-MINUS is to insert into the minuend, but <u>delete</u> from the subtrahend -- otherwise the insertion will not appear in the result, i.e. a ''side effect''.<br /> <br /> The examples D&B consider here (such as replacing a tuple for a requested insert, in order to preserve semantic consistency) all fail on other of their criteria -- especially causing ''side effects'', or risking causing ''side effects'' depending on other content of the base schema.<br /> <br /> Furthermore since they're concluding "there are very few situations in which view updates are possible", there is no requirement for "some additional semantics". 'Back off' the semantic requirements, and more views will be updatable-through.<br /> <br /> == The paper's contribution to [[Update through views: a possible approach]] ==<br /> <br /> The ''preserves semantic consistency'' ("Golden Rule") and ''no side effects'' ("Assignment Principle") are my prescription 1 and 2.<br /> <br /> D&B's aim for "compile time check on update translatability" is another implicit criterion/restraint on algorithms. It appears as my prescription 3.<br /> <br /> ''no extraneous updates'' and ''unique'' set of updates are my prescription 4 (necessary and sufficient/''essential'' tuples and attribute values) -- which is more explicit about what constitutes a "set of updates" and what it is for something in that set to be ''extraneous''.<br /> <br /> Can I express the prescriptions as succinctly as D&B's criteria?<br /> <br /> Given a semantically consistent schema extension '''$*''', we say that an update operation '''u''' on view extension '''V*''' is ''translatable'' if there is a set of tuple inserts, deletes and replacements '''U''' on '''$*''', together ''sufficient'' to produce the desired update on '''V*''', such that each tuple operation is ''necessary'' in '''U''', the ''precise effect'' on '''V*''' is as requested, '''U''' ''preserves semantic consistency'', and the ''translation is statically determinable'' purely from the form of the update request, the schema and view definition and the semantic integrity constraints.<br /> <br /> == References ==<br /> <br /> Dayal and Bernstein 1978 "On the Updatability of Relational Views”<br /> https://pdfs.semanticscholar.org/39f4/853a35a913c714c5f3956dbefd02916447c4.pdf<br /> <br /> See also [[Update through views: a possible approach#References]]</div>

Dave http://d2.reldb.org/index.php?title=User:Martin_King&diff=71 User:Martin King 2017-02-06T18:01:41Z

<p>Dave: Creating user page for new user.</p> <hr /> <div>First encountered Bill of Material networked file systems around 1970.<br /> <br /> Specialist in IBM IMS and SQL/DOS/VS hierarchical/network DBMS's from around 1972.<br /> <br /> Encountered Codd 1970 paper and IBM Peterlee PRTV RDMBS in 1975 while researching database design methods.<br /> <br /> Involved in ISO DBMS, SQL, and Conceptual Schema (based on ANSI/X3/SPARC SGDMS 1975 report) standardization from 1977 on.<br /> <br /> Specialist in IBM DB2 RDBS from pre-launch in early 1980's.<br /> <br /> Keen on Logic and declarative programming</div>

Dave http://d2.reldb.org/index.php?title=User_talk:Martin_King&diff=72 User talk:Martin King 2017-02-06T18:01:41Z

<p>Dave: Welcome!</p> <hr /> <div>'''Welcome to ''D Wiki''!'''<br /> We hope you will contribute much and well.<br /> You will probably want to read the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents help pages].<br /> Again, welcome and have fun! [[User:Dave|Dave]] ([[User talk:Dave|talk]]) 18:01, 6 February 2017 (UTC)</div>

Dave http://d2.reldb.org/index.php?title=User_talk:AntC&diff=51 User talk:AntC 2017-02-05T08:20:43Z

<p>Dave: Welcome!</p> <hr /> <div>'''Welcome to ''D Wiki''!'''<br /> We hope you will contribute much and well.<br /> You will probably want to read the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents help pages].<br /> Again, welcome and have fun! [[User:Dave|Dave]] ([[User talk:Dave|talk]]) 08:20, 5 February 2017 (UTC)</div>

Dave http://d2.reldb.org/index.php?title=User:AntC&diff=50 User:AntC 2017-02-05T08:20:42Z

<p>Dave: Creating user page for new user.</p> <hr /> <div>First encountered the RM with System/38 early 1980's.<br /> <br /> User and Programmer for SQL over 30 years.<br /> Always disappointed with it.<br /> <br /> Advocate for a Relational approach closer to ttm than to anything else.<br /> <br /> Joined the ttm forum ~12 years ago.<br /> <br /> Keen on Functional Programming -- especially Haskell.<br /> You need the power of something like its type system to bridge the impedance mis-match to relational.</div>

Dave http://d2.reldb.org/index.php?title=Main_Page&diff=38 Main Page 2016-05-23T16:35:14Z

<p>Dave: </p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's ''The Third Manifesto''], and were produced and curated by participants of the TTM mailing list.<br /> <br /> New visitors could start here with some [[RecommendedReading]].<br /> <br /> Articles hosted here:<br /> <br /> <blockquote><br /> [[Catalog]]<br /> </blockquote><br /> <br /> Consult the [//meta.wikimedia.org/wiki/Help:Contents User's Guide] for general information on using this wiki software.</div>

Dave http://d2.reldb.org/index.php?title=Main_Page&diff=37 Main Page 2016-05-23T16:34:39Z

<p>Dave: </p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's ''The Third Manifesto''], and were produced and curated by participants of the TTM mailing list.<br /> <br /> New visitors could start here with some [[RecommendedReading]].<br /> <br /> Articles hosted here:<br /> <br /> [[Catalog]]<br /> <br /> Consult the [//meta.wikimedia.org/wiki/Help:Contents User's Guide] for general information on using this wiki software.</div>

Dave http://d2.reldb.org/index.php?title=Main_Page&diff=36 Main Page 2016-05-23T16:34:25Z

<p>Dave: Index to content</p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's ''The Third Manifesto''], and were produced and curated by participants of the TTM mailing list.<br /> <br /> New visitors could start here with some [[RecommendedReading]].<br /> <br /> Articles hosted here:<br /> <br /> [Catalog]<br /> <br /> Consult the [//meta.wikimedia.org/wiki/Help:Contents User's Guide] for general information on using this wiki software.</div>

Dave http://d2.reldb.org/index.php?title=User_talk:Dandl&diff=30 User talk:Dandl 2016-05-17T08:33:09Z

<p>Dave: Welcome!</p> <hr /> <div>'''Welcome to ''D Wiki''!'''<br /> We hope you will contribute much and well.<br /> You will probably want to read the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents help pages].<br /> Again, welcome and have fun! [[User:Dave|Dave]] ([[User talk:Dave|talk]]) 09:33, 17 May 2016 (BST)</div>

Dave http://d2.reldb.org/index.php?title=User:Dandl&diff=29 User:Dandl 2016-05-17T08:33:08Z

<p>Dave: Creating user page for new user.</p> <hr /> <div>I’m a veteran developer and IT guy from Melbourne Australia.<br /> <br /> My background is commercial rather than academic, and Windows rather than Unix. I write C/C++, C# and over the years dozens of other languages. My particular interest is compiler technology and tools for developers. I wrote a commercially successful database-oriented language and runtime, which has been ported to just about every version of MS-DOS, OS/2, Windows and Unix, using proprietary ISAM, Btrieve, DB/2, MS SQL, Sybase and Oracle for its backend.<br /> <br /> I am currently working on Andl, a language inspired by and compliant with The Third Manifesto.</div>

Dave http://d2.reldb.org/index.php?title=User:ErwinSmout&diff=27 User:ErwinSmout 2016-05-09T19:56:02Z

<p>Dave: Creating user page for new user.</p> <hr /> <div>Old school software designer (high level languages are for sissies. Real men code assembler) (that was a joke). Insatiable curiosity re. making better tools & techniques for data management. Author of a generic testdatabase generator for IDMS. Author of a generic format converter between EDIFACT and XML formats. Author of SIRA_PRISE. Fairly recently converted to penguinista. And pretty enthusiastic ballroom dancer.</div>

Dave http://d2.reldb.org/index.php?title=User_talk:ErwinSmout&diff=28 User talk:ErwinSmout 2016-05-09T19:56:02Z

<p>Dave: Welcome!</p> <hr /> <div>'''Welcome to ''D Wiki''!'''<br /> We hope you will contribute much and well.<br /> You will probably want to read the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents help pages].<br /> Again, welcome and have fun! [[User:Dave|Dave]] ([[User talk:Dave|talk]]) 20:56, 9 May 2016 (BST)</div>

Dave http://d2.reldb.org/index.php?title=File:D2.png&diff=26 File:D2.png 2016-05-09T15:37:58Z

<p>Dave: Dave uploaded a new version of File:D2.png</p> <hr /> <div>Hastily constructed logo</div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:About&diff=25 D Wiki:About 2016-05-09T12:56:17Z

<p>Dave: Improved wording</p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's The Third Manifesto], and were produced and curated by participants of the TTM mailing list.<br /> <br /> The D<sup>2</sup> logo implies "D squared", or "D to the power of D", where '''D''' is both the abstract language family defined by The Third Manifesto and a general allusion to "database". It is also an intentional homage to the [http://c2.com/cgi/wiki C2 Wiki], the world's first Wiki run by its inventor Ward Cunningham, to which all Wikis owe enormous gratitude.<br /> <br /> To edit this Wiki, you must obtain an account via the "Request account" link in the upper right-hand corner of this page.</div>

Dave http://d2.reldb.org/index.php?title=Main_Page&diff=24 Main Page 2016-05-09T11:40:43Z

<p>Dave: Improve formatting</p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's ''The Third Manifesto''], and were produced and curated by participants of the TTM mailing list.<br /> <br /> Consult the [//meta.wikimedia.org/wiki/Help:Contents User's Guide] for information on using this wiki software.</div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:General_disclaimer&diff=23 D Wiki:General disclaimer 2016-05-09T11:38:08Z

<p>Dave: Created page with "This Wiki makes no guarantees of validity, correctness, accuracy, consistency, or applicability. Any content here should be used for entertainment purposes only. Any content..."</p> <hr /> <div>This Wiki makes no guarantees of validity, correctness, accuracy, consistency, or applicability. Any content here should be used for entertainment purposes only. Any content that purports to be advice or recommendations should be used with caution and only after having consulted relevant experts. Code examples should be run with caution, and assumed to be invalid and/or harmful until proven otherwise.</div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:About&diff=22 D Wiki:About 2016-05-09T11:06:31Z

<p>Dave: Tweak</p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's The Third Manifesto], and were produced and curated by participants of the TTM mailing list.<br /> <br /> The D<sup>2</sup> logo implies "D squared", or "D to the power of D", where '''D''' is both the abstract language family defined by The Third Manifesto and a general allusion to "database". It is also an intentional homage to the [http://c2.com/cgi/wiki C2 Wiki], the first Wiki invented by Ward Cunningham, to which all Wikis owe enormous gratitude.<br /> <br /> To edit this Wiki, you must obtain an account via the "Request account" link in the upper right-hand corner of this page.</div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:Privacy_policy&diff=21 D Wiki:Privacy policy 2016-05-09T11:05:36Z

<p>Dave: Tweak</p> <hr /> <div> <h2>What is this Privacy Policy for?</h2><br /> <p>This privacy policy is for this website [http://d2.reldb.org d2.reldb.org] and served by [http://RelDB.org RelDB.org] and Dave Voorhis and governs the privacy of its users who choose to use it. </p><br /> <p>The policy sets out the different areas where user privacy is concerned and outlines the obligations &amp; requirements of the users, the website and website owners. Furthermore the way this website processes, stores and protects user data and information will also be detailed within this policy.</p><br /> <h2>The Website</h2><br /> <p>This website and its owners take a proactive approach to user privacy and ensure the necessary steps are taken to protect the privacy of its users throughout their visiting experience. This website complies to all UK national laws and requirements for user privacy.</p><br /> <h4>Use of Cookies</h4><br /> <p>This website uses cookies to better the users experience while visiting the website. Where applicable this website uses a cookie control system allowing the user on their first visit to the website to allow or disallow the use of cookies on their computer / device. This complies with recent legislation requirements for websites to obtain explicit consent from users before leaving behind or reading files such as cookies on a user's computer / device.</p><br /> <p>Cookies are small files saved to the user's computers hard drive that track, save and store information about the user's interactions and usage of the website. This allows the website, through its server to provide the users with a tailored experience within this website.<br /><br /> Users are advised that if they wish to deny the use and saving of cookies from this website on to their computers hard drive they should take necessary steps within their web browsers security settings to block all cookies from this website and its external serving vendors.</p><br /> <h2>Contact &amp; Communication</h2><br /> <p>Users contacting this website and/or its owners do so at their own discretion and provide any such personal details requested at their own risk. Your personal information is kept private and stored securely until a time it is no longer required or has no use, as detailed in the Data Protection Act 1998. Every effort has been made to ensure a safe and secure form to email submission process but advise users using such form to email processes that they do so at their own risk.<br /><br /> </p><br /> <h2>External Links</h2><br /> <p>Although this website only looks to include quality, safe and relevant external links, users are advised adopt a policy of caution before clicking any external web links mentioned throughout this website.</p><br /> <p>The owners of this website cannot guarantee or verify the contents of any externally linked website despite their best efforts. Users should therefore note they click on external links at their own risk and this website and its owners cannot be held liable for any damages or implications caused by visiting any external links mentioned.</p><br /> <h2>Social Media Platforms</h2><br /> <p>Communication, engagement and actions taken through external social media platforms that this website and its owners participate on are custom to the terms and conditions as well as the privacy policies held with each social media platform respectively. </p><br /> <p>Users are advised to use social media platforms wisely and communicate / engage upon them with due care and caution in regard to their own privacy and personal details. This website nor its owners will ever ask for personal or sensitive information through social media platforms and encourage users wishing to discuss sensitive details to contact them through primary communication channels such as by telephone or email.</p><br /> <p>This website may use social sharing buttons which help share web content directly from web pages to the social media platform in question. Users are advised before using such social sharing buttons that they do so at their own discretion and note that the social media platform may track and save your request to share a web page respectively through your social media platform account.</p><br /> <h2>Shortened Links in Social Media</h2><br /> <p>This website and its owners through their social media platform accounts may share web links to relevant web pages. By default some social media platforms shorten lengthy URLs.<br /><br /> </p><br /> <p>Users are advised to take caution and good judgement before clicking any shortened URLs published on social media platforms by this website and its owners. Despite the best efforts to ensure only genuine URLs are published many social media platforms are prone to spam and hacking and therefore this website and its owners cannot be held liable for any damages or implications caused by visiting any shortened links.</p><br /> <h2>Resources &amp; Further Information</h2><br /> <ul><br /> <li>[http://www.legislation.gov.uk/ukpga/1998/29/contents Data Protection Act 1998]</li><br /> <li>[http://www.legislation.gov.uk/uksi/2003/2426/contents/made Privacy and Electronic Communications Regulations 2003]</li><br /> <li>[http://www.ico.gov.uk/for_organisations/privacy_and_electronic_communications/the_guide.aspx Privacy and Electronic Communications Regulations 2003 - The Guide]</li><br /> <li>[http://twitter.com/privacy Twitter Privacy Policy]</li><br /> <li>[http://www.facebook.com/about/privacy/ Facebook Privacy Policy]</li><br /> <li>[http://www.google.com/privacy.html Google Privacy Policy]</li><br /> <li>[http://www.linkedin.com/static?key=privacy_policy Linkedin Privacy Policy]</li><br /> </ul><br /> <p>v.1.0 May 2016</p></div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:Privacy_policy&diff=20 D Wiki:Privacy policy 2016-05-09T11:03:02Z

<p>Dave: Remove irrelevant bits.</p> <hr /> <div> <h2>What is this Privacy Policy for?</h2><br /> <p>This privacy policy is for this website [http://d2.reldb.org d2.reldb.org] and served by [http://RelDB.org RelDB.org] and Dave Voorhis and governs the privacy of its users who choose to use it. </p><br /> <p>The policy sets out the different areas where user privacy is concerned and outlines the obligations &amp; requirements of the users, the website and website owners. Furthermore the way this website processes, stores and protects user data and information will also be detailed within this policy.</p><br /> <h2>The Website</h2><br /> <p>This website and its owners take a proactive approach to user privacy and ensure the necessary steps are taken to protect the privacy of its users throughout their visiting experience. This website complies to all UK national laws and requirements for user privacy.</p><br /> <h4>Use of Cookies</h4><br /> <p>This website uses cookies to better the users experience while visiting the website. Where applicable this website uses a cookie control system allowing the user on their first visit to the website to allow or disallow the use of cookies on their computer / device. This complies with recent legislation requirements for websites to obtain explicit consent from users before leaving behind or reading files such as cookies on a user's computer / device.</p><br /> <p>Cookies are small files saved to the user's computers hard drive that track, save and store information about the user's interactions and usage of the website. This allows the website, through its server to provide the users with a tailored experience within this website.<br /><br /> Users are advised that if they wish to deny the use and saving of cookies from this website on to their computers hard drive they should take necessary steps within their web browsers security settings to block all cookies from this website and its external serving vendors.</p><br /> <h2>Contact &amp; Communication</h2><br /> <p>Users contacting this website and/or its owners do so at their own discretion and provide any such personal details requested at their own risk. Your personal information is kept private and stored securely until a time it is no longer required or has no use, as detailed in the Data Protection Act 1998. Every effort has been made to ensure a safe and secure form to email submission process but advise users using such form to email processes that they do so at their own risk.<br /><br /> </p><br /> <h2>External Links</h2><br /> <p>Although this website only looks to include quality, safe and relevant external links, users are advised adopt a policy of caution before clicking any external web links mentioned throughout this website.</p><br /> <p>The owners of this website cannot guarantee or verify the contents of any externally linked website despite their best efforts. Users should therefore note they click on external links at their own risk and this website and its owners cannot be held liable for any damages or implications caused by visiting any external links mentioned.</p><br /> <h2>Social Media Platforms</h2><br /> <p>Communication, engagement and actions taken through external social media platforms that this website and its owners participate on are custom to the terms and conditions as well as the privacy policies held with each social media platform respectively. </p><br /> <p>Users are advised to use social media platforms wisely and communicate / engage upon them with due care and caution in regard to their own privacy and personal details. This website nor its owners will ever ask for personal or sensitive information through social media platforms and encourage users wishing to discuss sensitive details to contact them through primary communication channels such as by telephone or email.</p><br /> <p>This website may use social sharing buttons which help share web content directly from web pages to the social media platform in question. Users are advised before using such social sharing buttons that they do so at their own discretion and note that the social media platform may track and save your request to share a web page respectively through your social media platform account.</p><br /> <h2>Shortened Links in Social Media</h2><br /> <p>This website and its owners through their social media platform accounts may share web links to relevant web pages. By default some social media platforms shorten lengthy URLs.<br /><br /> </p><br /> <p>Users are advised to take caution and good judgement before clicking any shortened URLs published on social media platforms by this website and its owners. Despite the best efforts to ensure only genuine URLs are published many social media platforms are prone to spam and hacking and therefore this website and its owners cannot be held liable for any damages or implications caused by visiting any shortened links.</p><br /> <h2>Resources &amp; Further Information</h2><br /> <ul><br /> <li><a href="http://www.legislation.gov.uk/ukpga/1998/29/contents" target="_blank">Data Protection Act 1998</a></li><br /> <li><a href="http://www.legislation.gov.uk/uksi/2003/2426/contents/made" target="_blank">Privacy and Electronic Communications Regulations 2003</a></li><br /> <li><a href="http://www.ico.gov.uk/for_organisations/privacy_and_electronic_communications/the_guide.aspx" target="_blank">Privacy and Electronic Communications Regulations 2003 - The Guide</a></li><br /> <li><a href="http://twitter.com/privacy" target="_blank">Twitter Privacy Policy</a></li><br /> <li><a href="http://www.facebook.com/about/privacy/" target="_blank">Facebook Privacy Policy</a></li><br /> <li><a href="http://www.google.com/privacy.html" target="_blank">Google Privacy Policy</a></li><br /> <li><a href="http://www.linkedin.com/static?key=privacy_policy" target="_blank">Linkedin Privacy Policy</a></li><br /> </ul><br /> <p>v.1.0 May 2016</p></div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:Privacy_policy&diff=19 D Wiki:Privacy policy 2016-05-09T11:01:37Z

<p>Dave: </p> <hr /> <div> <h2>What is this Privacy Policy for?</h2><br /> <p>This privacy policy is for this website [http://d2.reldb.org d2.reldb.org] and served by [http://RelDB.org RelDB.org] and Dave Voorhis and governs the privacy of its users who choose to use it. </p><br /> <p>The policy sets out the different areas where user privacy is concerned and outlines the obligations &amp; requirements of the users, the website and website owners. Furthermore the way this website processes, stores and protects user data and information will also be detailed within this policy.</p><br /> <h2>The Website</h2><br /> <p>This website and its owners take a proactive approach to user privacy and ensure the necessary steps are taken to protect the privacy of its users throughout their visiting experience. This website complies to all UK national laws and requirements for user privacy.</p><br /> <h4>Use of Cookies</h4><br /> <p>This website uses cookies to better the users experience while visiting the website. Where applicable this website uses a cookie control system allowing the user on their first visit to the website to allow or disallow the use of cookies on their computer / device. This complies with recent legislation requirements for websites to obtain explicit consent from users before leaving behind or reading files such as cookies on a user's computer / device.</p><br /> <p>Cookies are small files saved to the user's computers hard drive that track, save and store information about the user's interactions and usage of the website. This allows the website, through its server to provide the users with a tailored experience within this website.<br /><br /> Users are advised that if they wish to deny the use and saving of cookies from this website on to their computers hard drive they should take necessary steps within their web browsers security settings to block all cookies from this website and its external serving vendors.</p><br /> <h2>Contact &amp; Communication</h2><br /> <p>Users contacting this website and/or its owners do so at their own discretion and provide any such personal details requested at their own risk. Your personal information is kept private and stored securely until a time it is no longer required or has no use, as detailed in the Data Protection Act 1998. Every effort has been made to ensure a safe and secure form to email submission process but advise users using such form to email processes that they do so at their own risk.<br /><br /> </p><br /> <p>This website and its owners use any information submitted to provide you with further information about the products / services they offer or to assist you in answering any questions or queries you may have submitted. This includes using your details to subscribe you to any email newsletter program the website operates but only if this was made clear to you and your express permission was granted when submitting any form to email process. Or whereby you the consumer have previously purchased from or enquired about purchasing from the company a product or service that the email newsletter relates to. This is by no means an entire list of your user rights in regard to receiving email marketing material. <br /> Your details are not passed on to any third parties. </p><br /> <h2>External Links</h2><br /> <p>Although this website only looks to include quality, safe and relevant external links, users are advised adopt a policy of caution before clicking any external web links mentioned throughout this website.</p><br /> <p>The owners of this website cannot guarantee or verify the contents of any externally linked website despite their best efforts. Users should therefore note they click on external links at their own risk and this website and its owners cannot be held liable for any damages or implications caused by visiting any external links mentioned.</p><br /> <h2>Adverts and Sponsored Links</h2><br /> <p>This website may contain sponsored links and adverts. These will typically be served through our advertising partners, to whom may have detailed privacy policies relating directly to the adverts they serve. </p><br /> <p>Clicking on any such adverts will send you to the advertisers website through a referral program which may use cookies and will track the number of referrals sent from this website. This may include the use of cookies which may in turn be saved on your computers hard drive. Users should therefore note they click on sponsored external links at their own risk and this website and its owners cannot be held liable for any damages or implications caused by visiting any external links mentioned.</p><br /> <h2>Social Media Platforms</h2><br /> <p>Communication, engagement and actions taken through external social media platforms that this website and its owners participate on are custom to the terms and conditions as well as the privacy policies held with each social media platform respectively. </p><br /> <p>Users are advised to use social media platforms wisely and communicate / engage upon them with due care and caution in regard to their own privacy and personal details. This website nor its owners will ever ask for personal or sensitive information through social media platforms and encourage users wishing to discuss sensitive details to contact them through primary communication channels such as by telephone or email.</p><br /> <p>This website may use social sharing buttons which help share web content directly from web pages to the social media platform in question. Users are advised before using such social sharing buttons that they do so at their own discretion and note that the social media platform may track and save your request to share a web page respectively through your social media platform account.</p><br /> <h2>Shortened Links in Social Media</h2><br /> <p>This website and its owners through their social media platform accounts may share web links to relevant web pages. By default some social media platforms shorten lengthy URLs.<br /><br /> </p><br /> <p>Users are advised to take caution and good judgement before clicking any shortened URLs published on social media platforms by this website and its owners. Despite the best efforts to ensure only genuine URLs are published many social media platforms are prone to spam and hacking and therefore this website and its owners cannot be held liable for any damages or implications caused by visiting any shortened links.</p><br /> <h2>Resources &amp; Further Information</h2><br /> <ul><br /> <li><a href="http://www.legislation.gov.uk/ukpga/1998/29/contents" target="_blank">Data Protection Act 1998</a></li><br /> <li><a href="http://www.legislation.gov.uk/uksi/2003/2426/contents/made" target="_blank">Privacy and Electronic Communications Regulations 2003</a></li><br /> <li><a href="http://www.ico.gov.uk/for_organisations/privacy_and_electronic_communications/the_guide.aspx" target="_blank">Privacy and Electronic Communications Regulations 2003 - The Guide</a></li><br /> <li><a href="http://twitter.com/privacy" target="_blank">Twitter Privacy Policy</a></li><br /> <li><a href="http://www.facebook.com/about/privacy/" target="_blank">Facebook Privacy Policy</a></li><br /> <li><a href="http://www.google.com/privacy.html" target="_blank">Google Privacy Policy</a></li><br /> <li><a href="http://www.linkedin.com/static?key=privacy_policy" target="_blank">Linkedin Privacy Policy</a></li><br /> </ul><br /> <p>v.1.0 May 2016</p></div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:Privacy_policy&diff=18 D Wiki:Privacy policy 2016-05-09T11:00:06Z

<p>Dave: Fix URL</p> <hr /> <div> <h2>What is this Privacy Policy for?</h2><br /> <p>This privacy policy is for this website [http://d2.reldb.org] and served by [http://RelDB.org] and governs the privacy of its users who choose to use it. </p><br /> <p>The policy sets out the different areas where user privacy is concerned and outlines the obligations &amp; requirements of the users, the website and website owners. Furthermore the way this website processes, stores and protects user data and information will also be detailed within this policy.</p><br /> <h2>The Website</h2><br /> <p>This website and its owners take a proactive approach to user privacy and ensure the necessary steps are taken to protect the privacy of its users throughout their visiting experience. This website complies to all UK national laws and requirements for user privacy.</p><br /> <h4>Use of Cookies</h4><br /> <p>This website uses cookies to better the users experience while visiting the website. Where applicable this website uses a cookie control system allowing the user on their first visit to the website to allow or disallow the use of cookies on their computer / device. This complies with recent legislation requirements for websites to obtain explicit consent from users before leaving behind or reading files such as cookies on a user's computer / device.</p><br /> <p>Cookies are small files saved to the user's computers hard drive that track, save and store information about the user's interactions and usage of the website. This allows the website, through its server to provide the users with a tailored experience within this website.<br /><br /> Users are advised that if they wish to deny the use and saving of cookies from this website on to their computers hard drive they should take necessary steps within their web browsers security settings to block all cookies from this website and its external serving vendors.</p><br /> <p>This website uses tracking software to monitor its visitors to better understand how they use it. This software is provided by Google Analytics which uses cookies to track visitor usage. The software will save a cookie to your computers hard drive in order to track and monitor your engagement and usage of the website, but will not store, save or collect personal information. You can read Google's privacy policy here for further information [http://www.google.com/privacy.html" Google Privacy Policy].<br /><br /> </p><br /> <p>Other cookies may be stored to your computers hard drive by external vendors when this website uses referral programs, sponsored links or adverts. Such cookies are used for conversion and referral tracking and typically expire after 30 days, though some may take longer. No personal information is stored, saved or collected.</p><br /> <h2>Contact &amp; Communication</h2><br /> <p>Users contacting this website and/or its owners do so at their own discretion and provide any such personal details requested at their own risk. Your personal information is kept private and stored securely until a time it is no longer required or has no use, as detailed in the Data Protection Act 1998. Every effort has been made to ensure a safe and secure form to email submission process but advise users using such form to email processes that they do so at their own risk.<br /><br /> </p><br /> <p>This website and its owners use any information submitted to provide you with further information about the products / services they offer or to assist you in answering any questions or queries you may have submitted. This includes using your details to subscribe you to any email newsletter program the website operates but only if this was made clear to you and your express permission was granted when submitting any form to email process. Or whereby you the consumer have previously purchased from or enquired about purchasing from the company a product or service that the email newsletter relates to. This is by no means an entire list of your user rights in regard to receiving email marketing material. <br /> Your details are not passed on to any third parties. </p><br /> <h2>External Links</h2><br /> <p>Although this website only looks to include quality, safe and relevant external links, users are advised adopt a policy of caution before clicking any external web links mentioned throughout this website.</p><br /> <p>The owners of this website cannot guarantee or verify the contents of any externally linked website despite their best efforts. Users should therefore note they click on external links at their own risk and this website and its owners cannot be held liable for any damages or implications caused by visiting any external links mentioned.</p><br /> <h2>Adverts and Sponsored Links</h2><br /> <p>This website may contain sponsored links and adverts. These will typically be served through our advertising partners, to whom may have detailed privacy policies relating directly to the adverts they serve. </p><br /> <p>Clicking on any such adverts will send you to the advertisers website through a referral program which may use cookies and will track the number of referrals sent from this website. This may include the use of cookies which may in turn be saved on your computers hard drive. Users should therefore note they click on sponsored external links at their own risk and this website and its owners cannot be held liable for any damages or implications caused by visiting any external links mentioned.</p><br /> <h2>Social Media Platforms</h2><br /> <p>Communication, engagement and actions taken through external social media platforms that this website and its owners participate on are custom to the terms and conditions as well as the privacy policies held with each social media platform respectively. </p><br /> <p>Users are advised to use social media platforms wisely and communicate / engage upon them with due care and caution in regard to their own privacy and personal details. This website nor its owners will ever ask for personal or sensitive information through social media platforms and encourage users wishing to discuss sensitive details to contact them through primary communication channels such as by telephone or email.</p><br /> <p>This website may use social sharing buttons which help share web content directly from web pages to the social media platform in question. Users are advised before using such social sharing buttons that they do so at their own discretion and note that the social media platform may track and save your request to share a web page respectively through your social media platform account.</p><br /> <h2>Shortened Links in Social Media</h2><br /> <p>This website and its owners through their social media platform accounts may share web links to relevant web pages. By default some social media platforms shorten lengthy URLs.<br /><br /> </p><br /> <p>Users are advised to take caution and good judgement before clicking any shortened URLs published on social media platforms by this website and its owners. Despite the best efforts to ensure only genuine URLs are published many social media platforms are prone to spam and hacking and therefore this website and its owners cannot be held liable for any damages or implications caused by visiting any shortened links.</p><br /> <h2>Resources &amp; Further Information</h2><br /> <ul><br /> <li><a href="http://www.legislation.gov.uk/ukpga/1998/29/contents" target="_blank">Data Protection Act 1998</a></li><br /> <li><a href="http://www.legislation.gov.uk/uksi/2003/2426/contents/made" target="_blank">Privacy and Electronic Communications Regulations 2003</a></li><br /> <li><a href="http://www.ico.gov.uk/for_organisations/privacy_and_electronic_communications/the_guide.aspx" target="_blank">Privacy and Electronic Communications Regulations 2003 - The Guide</a></li><br /> <li><a href="http://twitter.com/privacy" target="_blank">Twitter Privacy Policy</a></li><br /> <li><a href="http://www.facebook.com/about/privacy/" target="_blank">Facebook Privacy Policy</a></li><br /> <li><a href="http://www.google.com/privacy.html" target="_blank">Google Privacy Policy</a></li><br /> <li><a href="http://www.linkedin.com/static?key=privacy_policy" target="_blank">Linkedin Privacy Policy</a></li><br /> </ul><br /> <p>v.1.0 May 2016</p></div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:Privacy_policy&diff=17 D Wiki:Privacy policy 2016-05-09T10:58:57Z

<p>Dave: Created page with " <h2>What is this Privacy Policy for?</h2> <p>This privacy policy is for this website [http://d2.reldb.org] and served by [http://RelDB.org] and governs the privacy of its us..."</p> <hr /> <div> <h2>What is this Privacy Policy for?</h2><br /> <p>This privacy policy is for this website [http://d2.reldb.org] and served by [http://RelDB.org] and governs the privacy of its users who choose to use it. </p><br /> <p>The policy sets out the different areas where user privacy is concerned and outlines the obligations &amp; requirements of the users, the website and website owners. Furthermore the way this website processes, stores and protects user data and information will also be detailed within this policy.</p><br /> <h2>The Website</h2><br /> <p>This website and its owners take a proactive approach to user privacy and ensure the necessary steps are taken to protect the privacy of its users throughout their visiting experience. This website complies to all UK national laws and requirements for user privacy.</p><br /> <h4>Use of Cookies</h4><br /> <p>This website uses cookies to better the users experience while visiting the website. Where applicable this website uses a cookie control system allowing the user on their first visit to the website to allow or disallow the use of cookies on their computer / device. This complies with recent legislation requirements for websites to obtain explicit consent from users before leaving behind or reading files such as cookies on a user's computer / device.</p><br /> <p>Cookies are small files saved to the user's computers hard drive that track, save and store information about the user's interactions and usage of the website. This allows the website, through its server to provide the users with a tailored experience within this website.<br /><br /> Users are advised that if they wish to deny the use and saving of cookies from this website on to their computers hard drive they should take necessary steps within their web browsers security settings to block all cookies from this website and its external serving vendors.</p><br /> <p>This website uses tracking software to monitor its visitors to better understand how they use it. This software is provided by Google Analytics which uses cookies to track visitor usage. The software will save a cookie to your computers hard drive in order to track and monitor your engagement and usage of the website, but will not store, save or collect personal information. You can read Google's privacy policy here for further information [ <a href="http://www.google.com/privacy.html" target="_blank">http://www.google.com/privacy.html </a>].<br /><br /> </p><br /> <p>Other cookies may be stored to your computers hard drive by external vendors when this website uses referral programs, sponsored links or adverts. Such cookies are used for conversion and referral tracking and typically expire after 30 days, though some may take longer. No personal information is stored, saved or collected.</p><br /> <h2>Contact &amp; Communication</h2><br /> <p>Users contacting this website and/or its owners do so at their own discretion and provide any such personal details requested at their own risk. Your personal information is kept private and stored securely until a time it is no longer required or has no use, as detailed in the Data Protection Act 1998. Every effort has been made to ensure a safe and secure form to email submission process but advise users using such form to email processes that they do so at their own risk.<br /><br /> </p><br /> <p>This website and its owners use any information submitted to provide you with further information about the products / services they offer or to assist you in answering any questions or queries you may have submitted. This includes using your details to subscribe you to any email newsletter program the website operates but only if this was made clear to you and your express permission was granted when submitting any form to email process. Or whereby you the consumer have previously purchased from or enquired about purchasing from the company a product or service that the email newsletter relates to. This is by no means an entire list of your user rights in regard to receiving email marketing material. <br /> Your details are not passed on to any third parties. </p><br /> <h2>External Links</h2><br /> <p>Although this website only looks to include quality, safe and relevant external links, users are advised adopt a policy of caution before clicking any external web links mentioned throughout this website.</p><br /> <p>The owners of this website cannot guarantee or verify the contents of any externally linked website despite their best efforts. Users should therefore note they click on external links at their own risk and this website and its owners cannot be held liable for any damages or implications caused by visiting any external links mentioned.</p><br /> <h2>Adverts and Sponsored Links</h2><br /> <p>This website may contain sponsored links and adverts. These will typically be served through our advertising partners, to whom may have detailed privacy policies relating directly to the adverts they serve. </p><br /> <p>Clicking on any such adverts will send you to the advertisers website through a referral program which may use cookies and will track the number of referrals sent from this website. This may include the use of cookies which may in turn be saved on your computers hard drive. Users should therefore note they click on sponsored external links at their own risk and this website and its owners cannot be held liable for any damages or implications caused by visiting any external links mentioned.</p><br /> <h2>Social Media Platforms</h2><br /> <p>Communication, engagement and actions taken through external social media platforms that this website and its owners participate on are custom to the terms and conditions as well as the privacy policies held with each social media platform respectively. </p><br /> <p>Users are advised to use social media platforms wisely and communicate / engage upon them with due care and caution in regard to their own privacy and personal details. This website nor its owners will ever ask for personal or sensitive information through social media platforms and encourage users wishing to discuss sensitive details to contact them through primary communication channels such as by telephone or email.</p><br /> <p>This website may use social sharing buttons which help share web content directly from web pages to the social media platform in question. Users are advised before using such social sharing buttons that they do so at their own discretion and note that the social media platform may track and save your request to share a web page respectively through your social media platform account.</p><br /> <h2>Shortened Links in Social Media</h2><br /> <p>This website and its owners through their social media platform accounts may share web links to relevant web pages. By default some social media platforms shorten lengthy URLs.<br /><br /> </p><br /> <p>Users are advised to take caution and good judgement before clicking any shortened URLs published on social media platforms by this website and its owners. Despite the best efforts to ensure only genuine URLs are published many social media platforms are prone to spam and hacking and therefore this website and its owners cannot be held liable for any damages or implications caused by visiting any shortened links.</p><br /> <h2>Resources &amp; Further Information</h2><br /> <ul><br /> <li><a href="http://www.legislation.gov.uk/ukpga/1998/29/contents" target="_blank">Data Protection Act 1998</a></li><br /> <li><a href="http://www.legislation.gov.uk/uksi/2003/2426/contents/made" target="_blank">Privacy and Electronic Communications Regulations 2003</a></li><br /> <li><a href="http://www.ico.gov.uk/for_organisations/privacy_and_electronic_communications/the_guide.aspx" target="_blank">Privacy and Electronic Communications Regulations 2003 - The Guide</a></li><br /> <li><a href="http://twitter.com/privacy" target="_blank">Twitter Privacy Policy</a></li><br /> <li><a href="http://www.facebook.com/about/privacy/" target="_blank">Facebook Privacy Policy</a></li><br /> <li><a href="http://www.google.com/privacy.html" target="_blank">Google Privacy Policy</a></li><br /> <li><a href="http://www.linkedin.com/static?key=privacy_policy" target="_blank">Linkedin Privacy Policy</a></li><br /> </ul><br /> <p>v.1.0 May 2016</p></div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:About&diff=16 D Wiki:About 2016-05-09T10:51:00Z

<p>Dave: Tweak</p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's The Third Manifesto], and were produced and curated by participants of the TTM mailing list.<br /> <br /> The D<sup>2</sup> logo implies "D squared", or "D to the power of D", where '''D''' is both the abstract language family defined by The Third Manifesto and a reference to "database". It is also an intentional homage to the [http://c2.com/cgi/wiki C2 Wiki], the first Wiki invented by Ward Cunningham, to which all Wikis owe enormous gratitude.<br /> <br /> To edit this Wiki, you must obtain an account via the "Request account" link in the upper right-hand corner of this page.</div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:About&diff=15 D Wiki:About 2016-05-09T10:46:19Z

<p>Dave: Tweak</p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's The Third Manifesto], and were produced and curated by participants of the TTM mailing list.<br /> <br /> The D<sup>2</sup> logo implies "D squared", or "D to the power of D", where '''D''' is the abstract language family defined by The Third Manifesto. It is also an intentional homage to the [http://c2.com/cgi/wiki C2 Wiki], the first Wiki invented by Ward Cunningham, to which all Wikis owe enormous gratitude.<br /> <br /> To edit this Wiki, you must obtain an account via the "Request account" link in the upper right-hand corner of this page.</div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:About&diff=14 D Wiki:About 2016-05-09T10:45:24Z

<p>Dave: Tweak</p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's The Third Manifesto], and were produced and curated by participants of the TTM mailing list.<br /> <br /> The D<sup>2</sup> logo implies "D squared", or "D to the power of D", where '''D''' is the abstract language family defined by The Third Manifesto. It is also an intentional homage to the [http://c2.com/cgi/wiki C2 Wiki], the first Wiki invented by Ward Cunningham, to which all Wikis owe enormous gratitude.<br /> <br /> To edit this Wiki, you must obtain an account via the link in the upper right-hand corner of this page.</div>

Dave http://d2.reldb.org/index.php?title=D_Wiki:About&diff=13 D Wiki:About 2016-05-09T10:43:55Z

<p>Dave: Created page with "This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's The Third Manifesto], and were produced and curated by partici..."</p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's The Third Manifesto], and were produced and curated by participants of the TTM mailing list.<br /> <br /> The D<sup>2 logo is meant to imply "D squared", or "D to the power of D", where '''D''' is the abstract language family defined by The Third Manifesto. It is also an intentional homage to the [http://c2.com/cgi/wiki C2 Wiki], the first Wiki.<br /> <br /> To edit this Wiki, you must obtain an account via the link in the upper right-hand corner of this page.</div>

Dave http://d2.reldb.org/index.php?title=User:Dave&diff=10 User:Dave 2016-05-09T10:18:10Z

<p>Dave: Created page with "Dave is Dave Voorhis, the lead developer of [http://reldb.org ''Rel''], an implementation of '''Tutorial D'''."</p> <hr /> <div>Dave is Dave Voorhis, the lead developer of [http://reldb.org ''Rel''], an implementation of '''Tutorial D'''.</div>

Dave http://d2.reldb.org/index.php?title=Main_Page&diff=9 Main Page 2016-05-09T10:15:23Z

<p>Dave: Really fix the URL this time... :-/</p> <hr /> <div>This collection of database writings and content are inspired by [http://thethirdmanifesto.com Date and Darwen's The Third Manifesto], and were produced and curated by participants of the TTM mailing list.<br /> <br /> Consult the [//meta.wikimedia.org/wiki/Help:Contents User's Guide] for information on using this wiki software.</div>

Dave http://d2.reldb.org/index.php?title=Main_Page&diff=8 Main Page 2016-05-09T10:14:21Z

<p>Dave: Fix URL</p> <hr /> <div>This collection of database writings and content are inspired by <a href="http://thethirdmanifesto.com">Date and Darwen's The Third Manifesto</a>, and were produced and curated by participants of the TTM mailing list.<br /> <br /> Consult the [//meta.wikimedia.org/wiki/Help:Contents User's Guide] for information on using this wiki software.</div>

Dave http://d2.reldb.org/index.php?title=Main_Page&diff=7 Main Page 2016-05-09T10:13:01Z

<p>Dave: </p> <hr /> <div>This collection of database writings and content are inspired by [[Date and Darwen's The Third Manifesto|http://thethirdmanifesto.com/]], and were produced and curated by participants of the TTM mailing list.<br /> <br /> Consult the [//meta.wikimedia.org/wiki/Help:Contents User's Guide] for information on using this wiki software.</div>

Dave http://d2.reldb.org/index.php?title=User:Jonathan_Leffler&diff=5 User:Jonathan Leffler 2016-05-09T09:58:09Z

<p>Dave: Creating user page for new user.</p> <hr /> <div>Long time user and developer of the Informix SQL DBMS running on Unix systems. Reader of many books by C J Date; I still have a copy of Introduction to Database Systems Volume II, for example. These days, not so active in database development — and somewhat tangentially using databases (the system I've been moved to uses a hodge-podge of 'NoSQL' DBMS, etc.) Sometimes, you don't get a choice in these matters.</div>

Dave http://d2.reldb.org/index.php?title=User_talk:Jonathan_Leffler&diff=6 User talk:Jonathan Leffler 2016-05-09T09:58:09Z

<p>Dave: Welcome!</p> <hr /> <div>'''Welcome to ''D Wiki''!'''<br /> We hope you will contribute much and well.<br /> You will probably want to read the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents help pages].<br /> Again, welcome and have fun! [[User:Dave|Dave]] ([[User talk:Dave|talk]]) 10:58, 9 May 2016 (BST)</div>

Dave http://d2.reldb.org/index.php?title=User:Greg&diff=3 User:Greg 2016-05-09T09:57:46Z

<p>Dave: Creating user page for new user.</p> <hr /> <div>Author of Dee (www.quicksort.co.uk), a Python-based implementation of a relational language aimed at conforming to The Third Manifesto.<br /> Author of ThinkSQL (www.thinksql.co.uk), a standards-compliant, open-source, SQL database server plus ODBC, JDBC and Python DB-API client libraries.<br /> <br /> (Your biography must be at least 50 words long.)</div>

Dave http://d2.reldb.org/index.php?title=User_talk:Greg&diff=4 User talk:Greg 2016-05-09T09:57:46Z

<p>Dave: Welcome!</p> <hr /> <div>'''Welcome to ''D Wiki''!'''<br /> We hope you will contribute much and well.<br /> You will probably want to read the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents help pages].<br /> Again, welcome and have fun! [[User:Dave|Dave]] ([[User talk:Dave|talk]]) 10:57, 9 May 2016 (BST)</div>

Dave http://d2.reldb.org/index.php?title=File:D2.png&diff=2 File:D2.png 2016-05-09T09:52:03Z

<p>Dave: Hastily constructed logo</p> <hr /> <div>Hastily constructed logo</div>

Dave