find records in t1 but not in t2, but has null value

[blackhorse]

SELECT column1,column2,column3
       FROM t1
       WHERE (column1,column2,column3) NOT IN
             (SELECT column1,column2,column3 FROM t2);

I can use this query to find records in t1 but not in t2. But this query only will work if column1, column2, column3 are NOT NULL.

Is there anyway that I can use the similar query but allow column1, column2, column3 has null value?

Just like using <=> replace = will cover the null value case?

Thanks!

[sneakyimp]

Not really clear what you are trying to do here. In order to reliably select records in t1 that are not in t2, checking on 3 fields seems a bit complicated. What your query is really saying is "show me all records in t1 that don't have an exact matching record in t2". If all 3 columns are NULL? That could be a pretty common record depending on how your code handles your db. If only one record is NULL, I would imagine your query would still work.