In Mysql, if you wanna test a row exists or not, you could also try EXISTS:

SELECT EXISTS(SELECT * FROM table1 WHERE ...)

and per the documentation, you can SELECT anything.

Traditionally, an EXISTS subquery starts with SELECT *, but it could begin with SELECT 5 or SELECT column1 or anything at all. Mysql ignores the SELECT list in such a subquery, so it makes no difference.

FYI:

• Subqueries with EXISTS or NOT EXISTS
• stackoverflow issue