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

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The INNER JOINThis brings up a design issue:Typically, when designing things likeEmployees table, we probably will never wantto delete an employee record, to prevent this sortof thing from happening.Instead, we might a Boolean field calledCurrentEmployee and a Date/Time fieldcalled TerminationDate to indicate when anemployee left the company.
The LEFT JOINThe LEFT JOIN specifies that all records fromthe left-hand table be returned, even if the recordhas no matching records in the right-hand table.If we used a LEFT JOIN in the previousexample, all Employee records would be returned,even employees who generated no Orders.In such a case, the employee record who had zeroothers would be returned exactly once, and thefields that came from the right-hand table wouldbe NULL in that record.
Page 1 and 2: Whirlwind Tour of SQL, Part 2Web an
Page 3 and 4: AGGREGATE FUNCTIONS
Page 5 and 6: Aggregate FunctionsConsider this co
Page 7 and 8: Aggregate FunctionsSince the name w
Page 9 and 10: Aggregate FunctionsIn general, you
Page 11 and 12: Aggregate FunctionsFunction UseAppl
Page 13 and 14: Aggregate FunctionsIf all we could
Page 15 and 16: Aggregate FunctionsYou do not have
Page 17 and 18: GroupingIn the first query, the sum
Page 19 and 20: GroupingIncidentally, the above is
Page 21 and 22: JOIN CLAUSES
Page 23 and 24: The JOIN ClauseJoins usually make u
Page 25 and 26: Design StrategiesThis is generally
Page 27 and 28: The JOIN ClauseThe join key or comm
Page 29 and 30: The JOIN ClauseThe above query will
Page 31 and 32: Speeding Things UpWe could have wri
Page 33 and 34: Relationships among TablesThe way w
Page 35 and 36: One-To-ManyOne-to-Many: The most li
Page 37 and 38: Showing RelationshipsIn the query w
Page 39 and 40: Showing RelationshipsNotice this re
Page 41 and 42: TYPES OF JOIN CLAUSES
Page 43 and 44: The INNER JOINThis is the default t
Page 45: The INNER JOINIn the above example,
Page 49 and 50: The RIGHT JOINThe RIGHT JOIN specif
Page 51 and 52: The OUTER JOINThe OUTER or FULL JOI
Page 53 and 54: The OUTER JOINThis means possibly g
Page 55 and 56: The CROSS JOINThis is a very odd ty
Page 57 and 58: The CROSS JOINHowever, when running
Page 59 and 60: Using JOIN and WHEREOf course, we c
Page 61 and 62: Using JOIN and ORDER BYWe can also
Page 63 and 64: Using JOIN and WHEREHere, the sort
Page 65 and 66: Compound JoinsFinal ResultsResults
Page 67 and 68: Compound JoinsThis example produces
Page 69 and 70: 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 and 122:
SQL TransactionsIn SQL, it might lo
Page 123 and 124:
SQL TransactionsThe opposite of a C
Page 125 and 126:
CONCLUSIONS
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