book

SQL and Relational Theory, 3rd Edition

by C.J. Date

November 2015

Intermediate to advanced

582 pages

16h 19m

English

O'Reilly Media, Inc.

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The relational model is much misunderstoodSome remarks on terminologyPrinciples not productsA review of the original modelModel vs. implementationProperties of relationsBase vs. derived relationsRelations vs. relvarsValues vs. variablesConcluding remarksExercisesAnswers

Types and relationsEquality comparisonsData value atomicityWhat’s a type?Scalar vs. nonscalar typesScalar types in SQLType checking and coercion in SQLCollations in SQLRow and table types in SQLConcluding remarksExercisesAnswers
What’s a tuple?Rows in SQLWhat’s a relation?Relations and their bodiesRelations are n-dimensionalRelational comparisonsTABLE_DUM and TABLE_DEETables in SQLColumn naming in SQLConcluding remarksExercisesAnswers
What’s wrong with duplicates?Duplicates: further issuesAvoiding duplicates in SQLWhat’s wrong with nulls?Avoiding nulls in SQLA remark on outer joinConcluding remarksExercisesAnswers
Updating is set levelRelational assignmentMore on candidate keysMore on foreign keysRelvars and predicatesRelations vs. typesExercisesAnswers
Some preliminariesMore on closureRestrictionProjectionJoinUnion, intersection, and differenceWhich operators are primitive?Formulating expressions one step at a timeWhat do relational expressions mean?Evaluating SQL table expressionsExpression transformationThe reliance on attribute namesExercisesAnswers
Exclusive unionSemijoin and semidifferenceExtendImage relationsDivideAggregate operatorsImage relations revisitedSummarizationSummarization revisitedGroup, ungroup, and relation valued attributes“What if” queriesA note on recursionWhat about ORDER BY?ExercisesAnswers
Type constraintsType constraints in SQLDatabase constraintsDatabase constraints in SQLTransactionsWhy database constraint checking must be immediateBut doesn’t some checking have to be deferred?Constraints and predicatesMiscellaneous issuesExercisesAnswers
Views are relvarsViews and predicatesRetrieval operationsViews and constraintsUpdate operationsWhat are views for?Views and snapshotsExercisesAnswers
Why do we need logic?Simple and compound propositionsSimple and compound predicatesQuantificationRelational calculusMore on quantificationSome equivalencesConcluding remarksExercisesAnswers
Some transformation lawsExample 1: Logical implicationExample 2: Universal quantificationExample 3: Implication and universal quantificationExample 4: Correlated subqueriesExample 5: Naming subexpressionsExample 6: More on naming subexpressionsExample 7: Dealing with ambiguityExample 8: Using COUNTExample 9: Another variationExample 10: UNIQUE quantificationExample 11: ALL or ANY comparisonsExample 12: GROUP BY and HAVINGExercisesAnswers
SELECT *Explicit tablesDot qualificationRange variablesSubqueries“Possibly nondeterministic” expressionsEmpty setsA simplified BNF grammarExercisesAnswers
The relational model vs. othersThe significance of theoryThe relational model definedDatabase variablesObjectives of the relational modelSome database principlesWhat remains to be done?
Vertical decompositionHorizontal decompositionWhat do the shaded entries mean?ConstraintsQueriesMore on predicatesExercisesAnswers
Functional segmentationShardingEventual consistencyThe Fernandez interview

Content preview from SQL and Relational Theory, 3rd Edition

Preface to the Third Edition

Much of the justification for the second edition applies to this third edition as well, but more so (as it were). Again the book has benefited from experience gained in teaching the material in various live classes. There are revisions of substance to many of the chapters, based on any or all of the following: changes to the SQL standard, improvements to Tutorial D, improvements in my own understanding of relational theory, better ways of presenting some of the material, and (in a few cases) simple corrections of errors. Also, in response to requests from readers:

I’ve increased the font size. (My own eyesight isn’t what it used to be, either.)
I’ve replaced all “smart quotes” in coding examples by “dumb quotes,” in order to help with cut and paste operations.
I’ve moved exercise answers to the chapter in which they belong (and set them in a different typeface), instead of putting them all in an appendix of their own at the back of the book.

I’ve also added an appendix on the new “NoSQL” systems, in which (as the title of that appendix indicates) I’ve tried to show what the relationship is between those systems and relational theory. Finally, textual and formatting improvements have been made throughout.

C. J. DateHealdsburg, California2015