That’s right. I defined an expression – a concatenation of two fields – and used the alias of that expression in another expression. Furthermore, I used the alias of the second expression in the WHERE clause. Gasp.
My workaround is to use
CROSS APPLY and define calculations in blocks there. This doesn’t work for aggregation operations, but in cases like Koen’s example, it does simplify the
WHERE clauses. This is a nicer solution, though.