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Home -> Community -> Usenet -> comp.databases.theory -> Re: How to ensure data consistency?
Felix E. Klee wrote:
> However, there still needs to be validation (with triggers?) that the
> id's of the specified specialization are non null.
Check constraints can be used for that:
CHECK ((type = 'A' AND a_id IS NOT NULL) OR (type != 'A' AND a_id IS NULL)) Received on Tue Sep 07 2004 - 10:21:25 CDT
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