mysql SELECT NOT IN () — disjoint set?

Question

I\'m having a problem getting a query to work, which I think should work. It\'s in the form

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


        

Answer 1

SELECT DISTINCT t1.* FROM t1 LEFT JOIN t2 ON (t1.a = t2.a AND t1.b = t2.b AND t1.c = t2.c) WHERE t2.a IS NULL