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

More documents

Recommendations

Info

Notes About the DELETE VerbEven if the employee dies or is fired, there is a lotof other information that must be kept around evenif the physical employee isn’t:• tax, health, and regulatory compliance information• data about work the employee did and so forth, whichwould be become difficult to reconstruct if thecorresponding employee record were removed.Instead, consider a field like CurrentStatus tocontain information about the actual employmentstate of the employee.
The UPDATE VerbThe UPDATE command allows you tochange the value of a field or fields in somesystematic way on all the selected records atonce.Since the UPDATE command can changedata in records, possible quite a lot of them,this too is a potentially dangerouscommand.
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 and 46:
The INNER JOINIn the above example,
Page 47 and 48:
The LEFT JOINThe LEFT JOIN specifie
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: The DELETE VerbOften, you should gi
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
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?