Aha - I followed your syntax completly and I got the correct result this time! Thank you so much for your help, much appreciated.

Regards

Fiona

Here's my suntax (based on your example)

select TAB1.B, TAB1.D,

Calc = SUM(TAB1.C) / (select cast(sum(TAB2.C) as decimal(19))

 from TABLE2 TAB2

 where TAB2.D = TAB1.D

AND  TAB2.B IN ('YES','NO')

AND  DATE BETWEEN '2005-10-01...

Hiya, your suggested method work in a way, but I can't get the actual output of the calculation right: using the same sourse data example I gave earlier,...