On Wed, 20 Feb 2002 13:51:12 -0800
Richard Emberson <emberson@phc.net> wrote:
> I have the following tables:
>
...
> -- a group set is a set of one or more groups
> CREATE TABLE group_sets (
Group_sets is already defined, isn't it ?
> group_id BIGINT,
> group_set_id BIGINT,
> ....
> FOREIGN KEY (group_id) REFERENCES groups (group_id),
> FOREIGN KEY (group_set_id) REFERENCES group_sets (group_set_id)
> );
>
> I want to:
> Find the group_set_id such that for a given user_id (input parameter)
> there is a one-to-one correspondence between the group_ids associated
> with the user_id and the group_ids associated with the group_set_id;
>
> for every group_id that the user_id has, the group_set_id also has it
> and for every group_id that the group_set_id has, the user_id also has it.
> If there is no such group_set_id, then return null.
>
> What query will generate the group_set_id?
I'm not sure whether or not I have understood what you described.
If I use organizations instead of the 2nd group_sets you were created,
presumably ...
-- using no joins
select org1.group_set_id from organizations as org1where exists (select org0.group_id from organizations
asorg0 where exists (select mem.group_id from membership as mem
where org0.group_id = mem.group_id and user_id = <<input parameter>>
group by mem.group_id having count(*) = 1
) and org1.group_id = org0.group_id group by org0.group_id having
count(*)= 1 )
;
-- using inner joins
select org2.group_set_id from (select org0.group_id from (select group_id from membership where
user_id= <<input parameter>> group by group_id having count(*) = 1 ) as mem
inner join organizations as org0 on (mem.group_id = org0.group_id) group by org0.group_id
having count(*) = 1 ) as org1 inner join organizations as org2 on (org1.group_id = org2.group_id)
;
Regards,
Masaru Sugawara
