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

As far as I know, NOT IN can only be used for 1 field at a time. And the field has to be specified in between "WHERE" and "NOT IN".

(Edit:) Try using a NOT EXISTS:

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

In addition, an inner join on a, b, and c being equal should give you all non-DISTINCT tuples, while a LEFT JOIN with a WHERE IS NULL clause should give you the DISTINCT ones, as Charles mentioned below.