November 17, 2008 at 12:03 am
hello
can i use UNIQUE constraint that do not calculate the NULL values in the column
November 17, 2008 at 12:12 am
On 2005, not easily. You can create an indexed view and put a unique clustered index on that, or you can define a calculated column and put the constraint on that.
On 2008 it's much easier - use a filtered unique index
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
November 17, 2008 at 12:16 am
Not with SQL Server 2005. You can create an indexed view on the table that will have a unique constraint and will not include NULL value, but I have to admit that when I tried using it in the past I gave it up because of all the set option that it required. By the way with SQL Server 2008 you can have where clause for indexes, so at that version making sure that some values will be unique and other won't, won't be a problem.
Adi
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