Oh, sorry if I didn't make that clear enough in my post

The expected result is

0.3 or similar for entering version=614 in the query and

approximately 0.6 for entering version=597 in the...

I've just realised that it doesn't work at all, for several reasons. The one being least my fault is the fact that

select count(t1.id) from table1 t1, table2 t2

will count...

Thank you for your help.

The EXISTS did not behave differently from IN, and I can't say I even understood the last answer, though it seems a much more thorough solution...

"And then there are developers who just know how to do sweet talk and pretend they know everything, in fact they do nothing right, you just do not know how...