Member Avatar for jglw

Say you have 3 tables

A (Key, a)
B (Key, b)
C (Key, c)

How would you select say 10 from A ordered by a, from 50 from B ordered by b, from 100 from C ordered by c? All the keys represents the same thing.

Thanks!

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Member Avatar for mwasif

What is 10, 50 and 100? See if you are looking for UNION.

Member Avatar for jglw

the top 10 etc once ordered

Member Avatar for mwasif

Did you look at UNION?

Member Avatar for jglw 
SELECT X.key, coalesce(a,0) AS ao, b FROM B RIGHT JOIN 
(SELECT * FROM B ORDER BY b LIMIT 0 , 100) AS X
ON B.key = X.key ORDER BY ao desc LIMIT 0, 50

is what I ended up with (I think...). This takes the top 100 once ordered by b, from which the top 50 are taken once ordered by a (I think... might have been a different JOIN, can't remember or be bothered to look).

I didn't look at UNION, maybe there's a neater solution. It seemed a bit long winded for such a common task.

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