Can you use multiple columns for a not in query?

Question

I recently saw someone post this as part of an answer to an SO query question:

SELECT DISTINCT a, b, c 
FROM t1 
WHERE (a,b,c) NOT IN 
   ( SELECT DISTINCT a,b,c FROM t2 )

I'm a bit confused, as I always thought that you can't use multiple columns for "NOT IN" ("where(a,b,c)", etc.). Is this correct SQL syntax? And how about MySQL?

Answer 1

Googling it suggests that it will work on some databases but not others. You can use this instead:

SELECT DISTINCT a, b, c 
FROM t1 
WHERE NOT EXISTS
   (SELECT 1 FROM t2 
    WHERE t1.a = t2.a AND t1.b = t2.b AND t1.c = t2.c)

Answer 2

It's a SQL extension. Oracle, PostgreSQL and MySQL have it. SQL Server 2005 does not have it. I'm not sure about others.