I'll wait a bit longer before passing certification 😉

I have never needed to filter on another table that the "directly" concerned one within a join. And so never wondered if...

GilaMonster (9/6/2013)

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The filter is on the join and it's an outer join. So the filter is done before the join then the left join joins in the matching rows, while...

btw, wouldn't it be better writing your example query more like :

SELECT * FROM t

WHERE (a<>0) and (b= 2 * a)

?

It will avoid the "CASE" term

Thanks for answers but the fact is that I don't need this "o.type = 'abcd'" and if I had done this query by myself I would never have written this...

Just went wrong due to the NULL value possibilty. 🙁

Some projects have already failed with such a lack of precision ... :w00t: