Re: AND or UNION

cscywong_at_ug.cs.ust.hk (Wong Chung Yin) wrote:
>Hi,
> Which one is more efficient?
>
>1. select * from empdemo where empdemo = 0 and empdemo = 1;
>2. select * from empdemo where empdemo = 0
> union
> select * from empdemo where empdemo = 1;

Hi there,

You should use 'IN' "in (0,1)" clause which will use index and it will be more efficient.

Regards

N.Prabhakar Received on Thu Feb 13 1997 - 00:00:00 CST