I'm with warey on this.  Please explain how the data are linked and give an example of the output you are trying to get to.

Can you post the exact error message that you are getting and the circumstances under which it is displayed?

Kenneth, if field1 is anything other than zero, your solution won't produce the required result: instead it will produce (field1 + (other calculations)), in the case where field2 is zero.

However,...

I think the Case statement is the way to go.  Something like this:

SELECT Field1, Field2, etc...

FROM tbl_Purchase

WHERE ((case field2

when 0 then 0

else field1/field2

end)

+ (other calculations)) > 0

Regards.

So, on insert to table2, need to set t2.refno to

select refno from table1 t1

where t1.email1 = t2.email2?

(where t2 is aliased to table2)

Is table1.email1 unique?  If not, obviously an issue here...

This is a bit confusing and needs a bit more info.  Are you saying that every time you create a record in table1, you need to create an associated record...

Nice thinking and thanks for the response - you've approached it from an angle I hadn't considered. 

But had to get on with it and have already written a wedge...