No literally, it's just "select * from event" !  It's an extreme example both due to it's simplicity and the size of the discrepancy, but very useful to illustrate my problem......

Thanks Colin.  In my experience QA usually does report worktable stats, but anyway in the case of the query I was using ("select * from table"), there are no disincts,...

Thanks Lucy, that article makes sense - it doesn't really explain the huge differences I'm seeing though.  Discrepancies in the hundreds, or even a few thousand, I can understand and...

Also you could consider using Unions i.e.

select *

from table1

where field1 = 'Row5'

union

select *

from table1

where field1 = 'Row3'

union

select *

from table1

where field1 = 'Row6'

union

select *

from table1

where field1 = 'Row100'

...slightly less readable than...