asked on

how to use group by in mulity table query?

I have two table that named table_user and table_area,
in table_user there some user records:
=========================
username,areacode,sex
=========================
azsd,0376,1
fake,0377,0
chome,0376,1
user3,0376,1
=========================

in table_area stores areacodes and their areaname
=========================
areacode,areaname
=========================
0376,xinyang
0377,nanyang
=========================

I want to make an query return back records like that:
=========================
username,areaname,sex
=========================
azsd,xinyang,1
fake,nanyang,0
chome,xinyang,1
user3,xinyang,1
=========================

which format sql phras that I would use?
I use that text and sql anlays can't pass though grammar check:
select "table_user".username, "table_area".areaname,"table_user".sex from "table_user","table_area","table_user" group by "table_user".areacode;
sure i don't think it can work.
the help files with oracle 9i have only few graphic,no more info....

thanks you read this question post by a poorman poor in english

pratikroy

You have a simple requirement :

Select a.username, b.areaname, a.sex
From table_user a, table_area b
Where a.areacode = b.areacode;

Hope this helps!

azsd

ASKER

yes it works,
unluckly the where statements occured an little things in my envorenment:
i have an user record

userx,0378,1

it will discarded and only 4 rows selected....
I want have these results

azsd,xinyang,1
fake,nanyang,0
chome,xinyang,1
user3,xinyang,1
userx,0378,1

how can i redirect the areacode that no exists in table_area as areaname?

azsd

ASKER

I have this idea:

Select a.username, b.areaname, a.sex
From table_user a, table_area b
Where a.areacode = b.areacode
union
select username,areacode as areaname,sex
from table_user
where areacode not in (select areacode from table_area);

but i think "not in (select)" will be slowest in oracle commands

ASKER CERTIFIED SOLUTION