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

Appendix G

Suggestions for Further Reading

A man ought to read just as inclination leads him;for what he reads as a task will do him little good.

—Samuel Johnson: quoted in Life of Johnson, by James Boswell (1791)

As the title says, this appendix gives some suggestions for further reading. The publications are listed in alphabetical order by author and chronological order within author.¹ Note: This book isn’t concerned with specific SQL products, and I therefore don’t mention any product oriented publications in this appendix. But many such publications exist, and I’m sure you’ll want to refer to one or more of them as well if you want to apply the ideas discussed in the present book to some individual project or product.

Surajit Chaudhuri and Gerhard Weikum: “Rethinking Database System Architecture: Towards a Self-Tuning RISC-style Database System,” Proc. 26th Int. Conf. on Very Large Data Bases, Cairo, Egypt (September 2000).

Among other things, this paper strongly endorses one of the messages of this book—viz., that SQL is complicated, confusing, and error prone. Here’s what Chaudhuri and Weikum have to say on the matter: “SQL is painful. A big headache that comes with a database system is the SQL language. It is the union of all conceivable features (many of which are rarely used or should be discouraged to use anyway) and is way too complex for the typical application developer. Its core, say selection-projection-join queries and aggregation, is extremely useful, but we ...