trouble with a mysql query
Posted: Mon Jun 09, 2003 5:09 pm
I'm having a bit of trouble.
I have a Mysql table with 4 fields:
id
userid
groupid
subgroupid
I want to find the number of unique-users within a subgroup.
normmaly I would do something like :
I can have multiple occurrences where a subgroupid and userid are the same, because subgroups can be refrecenced to multiple groups.
so I could have
id=1, userid=1, subgroupid=1, groupid=1
id=2, userid=1, subgroupid=1, groupid=2
id=3, userid=1, subgroupid=1, groupid=3
id=4, userid=2, subgroupid=1, groupid=1
id=5, userid=3, subgroupid=1, groupid=3
In my query that would count as 5 rows, but I only want it to count as 3.
Basically I want to be able to say "3 users are associated to subgroup 1".
Is there anyway I can do that?
--
thanks for any help
--pb
I have a Mysql table with 4 fields:
id
userid
groupid
subgroupid
I want to find the number of unique-users within a subgroup.
normmaly I would do something like :
Code: Select all
<?php
$sql = mysql_query("Select * from my_table where subgroup='".$id."'");
print mysql_num_rows($sql);
?>so I could have
id=1, userid=1, subgroupid=1, groupid=1
id=2, userid=1, subgroupid=1, groupid=2
id=3, userid=1, subgroupid=1, groupid=3
id=4, userid=2, subgroupid=1, groupid=1
id=5, userid=3, subgroupid=1, groupid=3
In my query that would count as 5 rows, but I only want it to count as 3.
Basically I want to be able to say "3 users are associated to subgroup 1".
Is there anyway I can do that?
--
thanks for any help
--pb