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Can I use identity columns in element sets?

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tenwit

Post subject: Can I use identity columns in element sets?

Posted: Mon Dec 19, 2005 8:58 pm

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Joined: Thu Dec 23, 2004 9:08 pm
Posts: 2008

I want to set up a simple collection (set probably, but a list or array will do fine) of integers, where the integer is allocated by the DB in a strictly incrementing way. That is, the table implementing the set will have only two columns: one being the foreign key to the containing table, and the other is an identity column (I'm using SQLServer).

Is there any way to tell hibernate that the value being added is to be generated by the DB, instead of added by the user? If <set> supported sql-insert then I could do it that way.

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tenwit

Post subject: Problem solved.

Posted: Mon Dec 19, 2005 10:44 pm

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Joined: Thu Dec 23, 2004 9:08 pm
Posts: 2008

Abusing the hard-coded positions in sql-insert, I gave this a go and it does exactly what I need:

Code:

<set name="Incrementing" table="IncrValues"  cascade="all">
  <key column="SetID"/>
  <element column="ValIncr" type="integer"/>
  <!-- The order and position of the ?s is vital (SetID, ValIncr),
    but I want to drop the ValIncr, as that is generated by the DB. -->
  <sql-insert>
    INSERT INTO IncrValues (SetID) VALUES ( ? ) -- ?
  </sql-insert>
</set>

Not especially elegant, but easily understood, I hope. The -- SQL comment causes the ValIncr set by the user to disappear. When I want a new value in the set, I just call