Module 13 (Introduction to SQL - Part 2).pdf

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SQL TransactionsThe COMMIT statement is a command to eitherperform all the SQL commands between theSTART and the COMMIT correctly, or to performnone of them.In systems like Oracle and SQL Server, there areextensive facilities for setting up transactions, andfor testing for errors and recovering from errors.A big difference between toy or demonstratorapplications and robust commercial applications isoften found in how thoroughly this is done.
SQL TransactionsThe opposite of a COMMIT is a ROLLBACK.If, during some of that data handling, wediscovered a computation error, or, worse,the system issued an error of its own (datatable corrupted, out of drive space, servercrash, etc.), we can cleanly and reliably rollback the state of the data tables to wherethey were before we began the transaction.
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Whirlwind Tour of SQL, Part 2Web an
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AGGREGATE FUNCTIONS
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Aggregate FunctionsConsider this co
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Aggregate FunctionsSince the name w
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Aggregate FunctionsIn general, you
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Aggregate FunctionsFunction UseAppl
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Aggregate FunctionsIf all we could
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Aggregate FunctionsYou do not have
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GroupingIn the first query, the sum
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GroupingIncidentally, the above is
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JOIN CLAUSES
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The JOIN ClauseJoins usually make u
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Design StrategiesThis is generally
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The JOIN ClauseThe join key or comm
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The JOIN ClauseThe above query will
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Speeding Things UpWe could have wri
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Relationships among TablesThe way w
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One-To-ManyOne-to-Many: The most li
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Showing RelationshipsIn the query w
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Showing RelationshipsNotice this re
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TYPES OF JOIN CLAUSES
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The INNER JOINThis is the default t
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The INNER JOINIn the above example,
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The LEFT JOINThe LEFT JOIN specifie
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The RIGHT JOINThe RIGHT JOIN specif
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The OUTER JOINThe OUTER or FULL JOI
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The OUTER JOINThis means possibly g
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The CROSS JOINThis is a very odd ty
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The CROSS JOINHowever, when running
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Using JOIN and WHEREOf course, we c
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Using JOIN and ORDER BYWe can also
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Using JOIN and WHEREHere, the sort
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Compound JoinsFinal ResultsResults
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Compound JoinsThis example produces
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Compound JoinsThe Sum(Ccur(...)) po
Page 71 and 72: Compound JOINsIn the JOIN section,
Page 73 and 74: The Self JOINThis is used to join a
Page 75 and 76: Non-Equi JOINsBut this will give us
Page 77 and 78: SubqueriesThis is a powerful techni
Page 79 and 80: SubqueriesThis example involves usi
Page 81 and 82: SubqueriesThe third example, involv
Page 83 and 84: SELECT … INTO StatementsEverythin
Page 85 and 86: SELECT … INTO StatementsThe list
Page 87 and 88: INSERT STATEMENTS
Page 89 and 90: The INSERT VerbThe easiest way to a
Page 91 and 92: The INSERT VerbWhere:• tablename
Page 93 and 94: INSERT ExampleEvery value given in
Page 95 and 96: INSERT ExampleAlso note that we nei
Page 97 and 98: The INSERT VerbBecause it is so use
Page 99 and 100: A Better ApproachOr… put the code
Page 101 and 102: Notes About INSERTThere are usually
Page 103 and 104: Notes about INSERTDEFAULT can be us
Page 105 and 106: The DELETE VerbThe DELETE verb is a
Page 107 and 108: The DELETE VerbHere is one that mig
Page 109 and 110: The DELETE VerbOften, you should gi
Page 111 and 112: The UPDATE VerbThe UPDATE command a
Page 113 and 114: UPDATE ExampleThis one might make m
Page 115 and 116: UPDATE ExampleOf course this might
Page 117 and 118: SQL TransactionsA critically import
Page 119 and 120: SQL TransactionsIt would be disastr
Page 121: SQL TransactionsIn SQL, it might lo
Page 125 and 126: CONCLUSIONS
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