Question

I have a problem dealing with the following construct:

SELECT *
FROM X
INNER JOIN
(
    SELECT TOP (X.IntegerAmount) *
    FROM Y
) AS Z ON X.ID = Z.X_ID

Is there a solution for this problem?

Answer 1

You can’t parameterise TOP with the value from another table

You can use a ranking function

SELECT *
FROM X
INNER JOIN
(
    SELECT ROW_NUMBER() OVER (ORDER BY SomeVal) as rn, *
    FROM Y
) AS Z ON X.ID = Z.X_ID
WHERE
   Z.rn <= X.IntegerAmount)

Or you’d have to make the derived query a UDF with a @topparameter

Note: you need an ORDER BY anyway

There are probably better ways to do what you actually want: this is answer to the what you actually asked which probably isn’t the same thing…