Hi Aaron,
Thanks very much, I really appreciate both the solution and the advice
about naming conventions. Your script worked fine and gives me an
example of what to do for other situations as well.
Because the logic structure of this software is in the front end
application rather than the database there is a strong need to keep the
naming of fields generic rather than specific, I am not using
pre-defined foreign keys at all. If I was building the database with a
purpose specific goal I would be doing what you say. I have found though
that when I label elements at different levels of the back end for one
purpose, they are less transportable in the long run. In this case the
naming conventions are actually stored in another table and applied as
aliases when needed. That way I can change the names and labels (for a
new client or industry) while the underlying structure remains the same.
I hope to increase interoperability in this way as well.
Thanks again for your help.
Kind regards
John T.
Aaron Bono wrote:
First of all, I must say it is very unfortunate that all the tables
have the same name for their primary key column. It made things
confusing at first when reading through the tables (the foreign key
names don't match the primary keys they map to). It also makes it
more likely you will do a join improperly.
Worse, your foriegn key names are very ambiguous. The name related_id
says nothing about what table it maps to. That means you need
documentation or the foreign key definitions (are you using foreign
key constraints?) to tell what is going on.
Anyway... on to solving your problem.
SELECT
permission.serial_id,
resource.name <http://resource.name/>,
actions.name <http://actions.name/>,
actions.classification,
actions.display_group
FROM permission
INNER JOIN policies ON (
policies.serial_id = permission.related_id
)
INNER JOIN actions ON (
actions.serial_id = policies.related_id
)
INNER JOIN resource ON (
-- This is tricky as policies maps to resources AND actions maps to
resources
-- so the real question is which one do you do? I did both.
policies.resource_id = resources.serial_id
AND
actions.related_id = resources.serial_id
)
WHERE
permission.user_id = '11' AND
policies.status = 'Active' AND
permission.status = 'Active'AND
actions.status = 'Active'AND
resource.status = 'Active'
;
I always discourage listing more than one table in the FROM clause.
Use INNER and OUTER JOINs - it is much easier to debug and it is
somewhat self documenting. That way, when you or another developer
look at this in the future, you understand right away how the tables
are being put together.
==================================================================
Aaron Bono
Aranya Software Technologies, Inc.
http://www.aranya.com
==================================================================
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
