Re: merge serval table into a table?

can you tell me when I execute a query which link these tables,which one would runs more faster.
In article <3A267AA0.FB7B5734_at_bmlam.de>,   no_spam_at_bmlam.de wrote:
> I would create the table structure first (this way you can specify a
> primary key) and then copy the rows from the other tables into the
 new one:
>
> insert into new_table
> select * from a1
> union all
> select * from a2
> union all
> select * from a3
> ... and so on.
>
> If you dont have enough space, you can "merge" and drop the tables
 one by
> one.
>
> wy_at_fudan.edu wrote:
>
> > 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.
>
> --
> To reply to me directly, please mail to: bmlam at online dot de
>
>

Sent via Deja.com http://www.deja.com/
Before you buy. Received on Sun Dec 03 2000 - 21:30:03 CST