Posted By: smb
I’m writing an SQL Query, where a few of the columns returned need to be calculated depending on quite a lot of conditions.
I’m currently using nested case statements, but its getting messy. Is there a better (more organised and/or readable) way?
(I am using Microsoft SQL Server, 2005)
A simplified example:
SELECT col1, col2, col3, CASE WHEN condition THEN CASE WHEN condition1 THEN CASE WHEN condition2 THEN calculation1 ELSE calculation2 END ELSE CASE WHEN condition2 THEN calculation3 ELSE calculation4 END END ELSE CASE WHEN condition1 THEN CASE WHEN condition2 THEN calculation5 ELSE calculation6 END ELSE CASE WHEN condition2 THEN calculation7 ELSE calculation8 END END END AS 'calculatedcol1', col4, col5 -- etc FROM table
You could try some sort of COALESCE trick, eg:
SELECT COALESCE( CASE WHEN condition1 THEN calculation1 ELSE NULL END, CASE WHEN condition2 THEN calculation2 ELSE NULL END, etc... )