Use column aliases in WHERE clauses without creating lengthy SQL queries

摘要

Note: Did you notice we didn't mention the ORDER BY clause in our list of verboten locations for a column alias? That's because, in an ORDER BY clause, it's allowed. Unlike WHERE and other SQL clauses, ORDER BY isn't actually a T-SQL clause. Strictly speaking; it's really a cursor operator. As such, it doesn't suffer the same limitations as bona fide clauses, and hence, they're perfectly free to reference column aliases.