Select * From dbo.aptax_sy
Where
(not exists( select dbo.aptax_invno from dbo.aptax where dbo.aptax.branch_id+dbo.aptax.aptax_invno = dbo.aptax_sy.branch_id+dbo.aptax_sy.aptax_invno));
Could you put some more effort in the question please? Like posting it in the right forum, giving a bit more information about which version you're using, what you've tried yourself which failed etc.