Thanks for that. I had come to the same conclusion myself. Seems a pity that CASE could not be used a quirk of SQL Server!!

I have tried that but get a syntax error line 14 Incorrect syntax near the keyword 'SELECT' line 15 Incorrect syntax near ')' line 14 ELSE SELECT 'W' UNION SELECT 'R' line 15 END) I have tried just the SELECT CASE part of the Query with no group key and line 14 as ELSE 'W'+','+'R' and this returns W,R. Even tried doubling up the quotes viz: ELSE '''W'''+','+'''R''' which returns 'W','R' but this also fails to bring back rows

I have the code below which works fine in the two WHEN parts. However when the two parts fail, because the group key is absent (a valid condition) I want to choose both, hence the ELSE part. But no rows are returned in this case. mantype can be W or R SELECT * FROM callsigns WHERE mantype IN (SELECT CASE WHEN EXISTS(SELECT 1 FROM group gr1 WHERE gr1.group_key = 'RA' AND gr1.gra_valid = 1 AND 0 = (gr1.gra_flags & 7)^3) THEN 'R' WHEN EXISTS(SELECT 1 FROM group gr2 WHERE gr2.group_key = 'RA' AND gr2.gra_valid = 1 AND 0 = (gr2.gra_flags & 7)^1) THEN 'W' ELSE 'W'+','+'R' END)