integrity rules
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Integrity Rules
Angelica R. MalaluanBSA 2-7
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• Two integrity rules must beenforced by a relational DBMS
–ntity integrity
–Referential integrity
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ntity Integrity
• !o "eld t#at is $art of $rimary %eymay acce$t null &alues
• To s$ecify $rimary %ey in S'() – nter a PRIMARY KEY clause in eit#er
an A(TR TAB( or a *RAT TAB(command
•
To designate $rimary %ey in Access) – Select $rimary %ey "eld in Table Design
&iew
– *lic% t#e +rimary ,ey button in t#e
Tools grou$ on t#e TAB( T(S
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ntity Integrity
• S'( command to s$ecify a $rimary%ey)
PRIMARY KEY (CustomerNum)
• S'( command w#en more t#an one"eld included)
– PRIMARY KEY (OrderNum, PartNum)
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ntity Integrity
FIGURE 4-15: Specifying a primary key in Access
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ntity Integrity
FIGURE 4-1: Specifying a primary key c!nsis"ing !f m!re"#an !ne $e%& in Access