Hi Cetin

DOH!

Yes the old order or evaluation of operators has bitten me. I should have known better and realised.
Thanks. I did that but unfortunately I'm still getting the same spurious answer.

Terry

>Terry,
>I'd start by putting parentheses around "or" "and" blocks of where clause. As I interpret it now:
>

>where ET.date BETWEEN ldStartCurr and ldEndCurr ;
>  OR 	( ET.date BETWEEN ldStartPrev and ldEndPrev ;
>  AND 	NOT EXISTS ... )
>

>Probably you meant:
>

>where ( ET.date BETWEEN ldStartCurr and ldEndCurr ;
>  OR 	ET.date BETWEEN ldStartPrev and ldEndPrev ) ;
>  AND 	NOT EXISTS ...
>

>Cetin