How do I combine check constraint with unique constraint

• Walter Tucholski

  Ten Centuries

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  May 30, 2006 at 6:22 am

  #168380

  Does anyone know how or if I can combine a check constraint with unique constraint? For example tbla has 3 columns, col1, col2, col3. col1 and col2 must be unique if col3 is a certain value.

• BeerBeerBeer

  SSCarpal Tunnel

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  June 5, 2006 at 4:32 pm

  #641841

  Sounds to me like you might need to control that particular scenario programmatically.

  From my understanding, you usually define uniqueness via an index but I don't believe they are conditional.

  As for looking at it from the other end, i.e. creating a check constraint, I don't think you can access the whole table to see if a certain value exists - unless you can use a user defined function to confirm the existence of the the required value. Can't say I've tried it but it might be worth a look.

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  Regards,

  Steve

  Life without beer is no life at all

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