You could. But `SELECT 1` is a very common pattern in SQL Server, intended exactly to declare intent to the reader that "this subquery doesn't return any real data" - in the event the `EXISTS` that surrounds it isn't enough of a clue. You could use `SELECT NULL` or `SELECT 0` or `SELECT *` or `SELECT 12/0` and the behavior would be identical, but most of those would likely raise even more questions to an inexperienced reader than `SELECT 1`.
