On 26-Feb-2003 Jun.Han@stripped wrote:
> Yes , I had use this query statement in my MySQL server,
> But I have a query about it.
> Why are you use "WHERE a.groupname=b.groupname AND members.id=b.memberid
> AND a.memberid=1"?
> Can you give me a explain or give me a advise!
>
Sure.
mysql> SELECT DISTINCT members.* FROM members, groups as a, groups as b
-> WHERE a.groupname=b.groupname AND members.id=b.memberid
-> AND a.memberid=1;
The 'a.memberid=1' clause looks up the groups that member 1 belongs to in the
groups table (as a), giving 'group1' & 'group2'.
Then it joins back against the groups table (as b) with the
'a.groupname=b.groupname' clause to get the folks that belong to these
group(s).
Finally the 'members.id=b.memberid' bit selects the records out of the members
table, with the DISTINCT function suppressing any duplicates.
Clear as mud?
(I could've be a little more obvious if I'd put the 'a.memberid=1' clause
first. Sorry ...)
Regards,
--
Don Read dread@stripped
-- It's always darkest before the dawn. So if you are going to
steal the neighbor's newspaper, that's the time to do it.
(53kr33t w0rdz: sql table query)
