merge serval table into a table?

I have created serval tables which have the same structure. eg.
create table A1 /*contain less then 100 records*/
(code char(2),

 value char(10),
 primary key code);
and Table A2,A3,A4 is the same ,record the different information.

some one advised me that I should merge them into one table like below: create table A
(id char(2), /*it should be A1 ..A4*/

 code char(2),
 value char(10),
primary key(id,code));

I want to know if I have a sql,the sql need link all of them:

select * from b,a1,a2,a3,a4
where

 b.code1 = a1.code
 b.code2 = a2.code
 b.code3 = a3.code
 b.code4 = a4.code

or

select * from b,a a1,a a2,a a3,a a4
where

 b.code1 = a1.code and a1.id='A1'
 b.code2 = a2.code and a1.id='A2'
 b.code3 = a3.code and a1.id='A3'
 b.code4 = a4.code and a1.id='A4'

which one run in higher performance!

Any suggestion are apreciated!

Thanks.

Sent via Deja.com http://www.deja.com/
Before you buy. Received on Thu Nov 30 2000 - 02:22:00 CST