The auto-added "FROM" feature is pretty slick for enabling JOINs within a DELETE. Allowing this to be explicit in 8.1 is going to be even better.
Since DELETEing from pg_users is an unsupported way to remove users, I am going to use the procedure in the end. It's a little-modified version of Patrick's code:
CREATE OR REPLACE FUNCTION removeUsersFromGroup( groupName name ) RETURNS int4 AS $$
DECLARE
userRecord RECORD;
numUsersDropped int4 := 0;
BEGIN
FOR userRecord IN
SELECT usename FROM pg_user,pg_group
WHERE usesysid = ANY (grolist)
AND groname = groupName
LOOP
numUsersDropped := numUsersDropped + 1;
EXECUTE('DROP USER ' || userRecord.usename);
END LOOP;
RETURN numUsersDropped;
END
$$ LANGUAGE 'plpgsql';
Thanks again for the help,
David J. Sankel
On 8/31/05, David Sankel <camior@xxxxxxxxx> wrote:
Hello List,
I'm trying to delete all the users from a group and it seems as though there isn't sufficient array functionality to do it.
The pg_group columns:
http://www.postgresql.org/docs/8.0/interactive/catalog-pg-group.html
The pg_user columns:
http://www.postgresql.org/docs/8.0/interactive/view-pg-user.html
After having a peek at the above, we know we can see all the users in a group with this:
SELECT *
FROM pg_user, pg_group
WHERE usesysid = ANY (grolist)
AND groname = 'somegroupname';
"ANY" is a function that can tell if a value is in an array:
http://www.postgresql.org/docs/8.0/interactive/arrays.html#AEN5491
Okay, that select function worked fine, but if we want to delete we cannot use a join (implicit by the ',') to help us out. So the following should work:
DELETE FROM pg_user
WHERE usesysid = ANY ( SELECT grolist
FROM pg_group
WHERE groname = 'somegroupname' )
But, alas, it doesn't. Neither does any combination of IN and ANY. It seems to me like this should work since the same syntax works if we weren't talking about arrays.
So, how can we delete all users within a specified group? Is there a bug or is the above code incorrect?
When testing the above delete function, I found it useful to substitute "SELECT *" for "DELETE" to get non-destructive queries.
Thanks for any help,
David J. Sankel
