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* A Not Join
@ 2005-11-01 14:27 L van der Walt <mailing@lani.co.za>
0 siblings, 3 replies; 4+ messages in thread
From: L van der Walt @ 2005-11-01 14:27 UTC (permalink / raw)
To: pgsql-sql; pgsql-general@postgresql.org
I have three table:
Users - Contains username, ID etc...
Permissions - A permission name and ID
Link up table - The user.id and permission.id
If a user.id and a permission.id row exists in the linkuptable the user
have that permission granted.
With the statement below I can see the permissions a user have.
SELECT users.username, permissions.name
FROM users INNER JOIN linkuptable
ON (users.id = linkuptable.userid)
INNER JOIN permissions
ON (permissions.id = linkuptable.permissionid)
WHERE users.username = 'DummyUser'
How do I see the permissions that user DON'T have with a fast SQL statement.
Thus, a NOT the statement for the above SQL statement
Regards
Lani
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: A Not Join
@ 2005-11-01 15:15 Jim C. Nasby <jnasby@pervasive.com>
parent: L van der Walt <mailing@lani.co.za>
2 siblings, 0 replies; 4+ messages in thread
From: Jim C. Nasby @ 2005-11-01 15:15 UTC (permalink / raw)
To: L van der Walt <mailing@lani.co.za>; +Cc: pgsql-sql; pgsql-general@postgresql.org
On Tue, Nov 01, 2005 at 04:27:01PM +0200, L van der Walt wrote:
> I have three table:
> Users - Contains username, ID etc...
> Permissions - A permission name and ID
> Link up table - The user.id and permission.id
>
> If a user.id and a permission.id row exists in the linkuptable the user
> have that permission granted.
>
> With the statement below I can see the permissions a user have.
>
> SELECT users.username, permissions.name
> FROM users INNER JOIN linkuptable
> ON (users.id = linkuptable.userid)
> INNER JOIN permissions
> ON (permissions.id = linkuptable.permissionid)
> WHERE users.username = 'DummyUser'
>
> How do I see the permissions that user DON'T have with a fast SQL statement.
>
> Thus, a NOT the statement for the above SQL statement
LEFT JOIN permissions ON (...)
WHERE permissions.id IS NULL
You might have to do the NULL check in a HAVING clause instead... try
it.
BTW, this is probably better asked on pgsql-sql.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: A Not Join
@ 2005-11-02 02:28 Jerry Sievers <jerry@jerrysievers.com>
parent: L van der Walt <mailing@lani.co.za>
2 siblings, 0 replies; 4+ messages in thread
From: Jerry Sievers @ 2005-11-02 02:28 UTC (permalink / raw)
To: pgsql-general@postgresql.org
L van der Walt <mailing@lani.co.za> writes:
> I have three table:
> Users - Contains username, ID etc...
> Permissions - A permission name and ID
> Link up table - The user.id and permission.id
>
> If a user.id and a permission.id row exists in the linkuptable the user
> have that permission granted.
>
> With the statement below I can see the permissions a user have.
>
> SELECT users.username, permissions.name
> FROM users INNER JOIN linkuptable
> ON (users.id = linkuptable.userid)
> INNER JOIN permissions
> ON (permissions.id = linkuptable.permissionid)
> WHERE users.username = 'DummyUser'
>
> How do I see the permissions that user DON'T have with a fast SQL statement.
>
Simple.
select permname
from permissions
where permid not in (
select permid
from linkage
where userid = 'dummy'
);
Or... a slick way to get the anti-permission for the whole bunch of
users is to;
cross join the userids with permids and then EXCEPT SELECT from
linkage table to filter out the active permissions.
Have fun!
--
-------------------------------------------------------------------------------
Jerry Sievers 305 854-3001 (home) WWW ECommerce Consultant
305 321-1144 (mobile http://www.JerrySievers.com/
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: A Not Join
@ 2005-11-21 20:16 stig erikson <stigerikson_nospam_@yahoo.se>
parent: L van der Walt <mailing@lani.co.za>
2 siblings, 0 replies; 4+ messages in thread
From: stig erikson @ 2005-11-21 20:16 UTC (permalink / raw)
To: pgsql-sql
L van der Walt wrote:
> I have three table:
> Users - Contains username, ID etc...
> Permissions - A permission name and ID
> Link up table - The user.id and permission.id
>
> If a user.id and a permission.id row exists in the linkuptable the user
> have that permission granted.
>
> With the statement below I can see the permissions a user have.
>
> SELECT users.username, permissions.name
> FROM users INNER JOIN linkuptable
> ON (users.id = linkuptable.userid)
> INNER JOIN permissions
> ON (permissions.id = linkuptable.permissionid)
> WHERE users.username = 'DummyUser'
>
> How do I see the permissions that user DON'T have with a fast SQL
> statement.
>
> Thus, a NOT the statement for the above SQL statement
>
> Regards
>
> Lani
>
what you need to do is select all possible permissions and then remove the
permissions that exist. try somthing like:
SELECT permissions.name
FROM permissions.name
WHERE permission.permissionid NOT IN
( SELECT permissions.permissionid
FROM users INNER JOIN linkuptable
ON (users.id = linkuptable.userid)
INNER JOIN permissions
ON (permissions.id = linkuptable.permissionid)
WHERE users.username = 'DummyUser'
)
^ permalink raw reply [nested|flat] 4+ messages in thread
end of thread, other threads:[~2005-11-21 20:16 UTC | newest]
Thread overview: 4+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2005-11-01 14:27 A Not Join L van der Walt <mailing@lani.co.za>
2005-11-01 15:15 ` Jim C. Nasby <jnasby@pervasive.com>
2005-11-02 02:28 ` Jerry Sievers <jerry@jerrysievers.com>
2005-11-21 20:16 ` stig erikson <stigerikson_nospam_@yahoo.se>
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