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UniqueConstraint

Treimin Clark
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Joined: Nov 12, 2008
Posts: 757
HeadFirst [surl='http://www.coderanch.com/forums/f-11/EJB-JEE' class='api' title='the JavaRanch JEE forum wrote:EJB[/surl] 3.0 Book]The @Table.UniqueConstraint attribute allows you to specify unique column constraint.


JPA Specs- (9.1.4) wrote:The UniqueConstraint annotation is used to specify that a unique constraint is to be included in the generated DDL for a primary or secondary table.


But I didn't understand what is this "unique column constraint"


Christophe Verré
Sheriff

Joined: Nov 24, 2005
Posts: 14688
    
  16

It allows to generate unique constraints in the DDL. Unique constraints are explained here. (I don't think this kind of annotation is at the exam, but who knows...)


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Treimin Clark
Ranch Hand

Joined: Nov 12, 2008
Posts: 757
Christophe Verré wrote:It allows to generate unique constraints in the DDL. Unique constraints are explained here. (I don't think this kind of annotation is at the exam, but who knows...)


Thanks Christophe
 
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subject: UniqueConstraint