Re: Need a query to get the difference of two tables

[Michael Stassen]

Roger Baklund wrote:
Harish wrote:
Hi,
I apprecaite anybody replying me with an equvalent query for this:
I am using mysql 4.0.21
select a.address from a where a.id not in (select b.iid from b where
b.message='y')

This can be done with a left join:
select a.address
  from a
  left join b on b.iid=a.id
  where b.iid is null;
That's not equivalent, because it leaves out a condition.  I think it 
should be
  SELECT a.address
  FROM a
  LEFT JOIN b ON a.id = b.iid AND b.message='y'
  WHERE b.iid IS NULL;
Michael
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