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