Frequent visitors might recall a thread earlier in the spring regarding optional parameters to a stored procedure (the earlier posts are here, here, and here). The question had basically boiled down to whether there was single-statement syntax available which would preclude the necessity to use dynamic SQL to resolve this requirement.
When we last checked in on this topic in April, I had nominated this syntax as a resolution for this issue:
WHERE y1 = ISNULL(@p1, y1)
AND y2 = ISNULL(@p2, y2)
AND y3 = ISNULL(@p3, y3)
AND y4 = ISNULL(@p4, y4)
I’m still looking into solutions to this issue. I’ve found one so far which requires use of a magic number, which works for numeric data but not for the general case:
DECLARE @constant INT
— set @constant to some value that doesn’t occur in your data
SET @constant = –32687
— now run the new syntax
WHERE ISNULL(y1, @constant) = ISNULL(@p1, ISNULL(y1, @constant))
AND ISNULL(y2, @constant) = ISNULL(@p2, ISNULL(y2, @constant))
AND ISNULL(y3, @constant) = ISNULL(@p3, ISNULL(y3, @constant))
AND ISNULL(y4, @constant) = ISNULL(@p4, ISNULL(y4, @constant))
— the syntax above returns correct results and is easier to code than dynamic sql
— its only downfall is that it requires a magic number
I’m still looking for datatype-agnostic syntax; although one could code this up with a @constant of each datatype (or one for each column if need be), that approach just multiplies the “magic number” issue.
I’ll let you know what I find..