Conditional Join (or something along those lines)

Hey folks,

I'm what I might call a "novice hack" at SQL in general, so forgive any
blatant oversighs on my part.

My problem is this, I have three tables as such:

region
===========
region_id
region_name
region_no

contact
===========
contact_id
name_first
name_last
email

contact_join
============
contact_id
parent_id
parent_table
relationship

The contact_join table works by holding the name of the table the contact is
for in the parent_table field, and the id of the record in that table.

A simple example of the three tables might be:

region:
23, 'South / Florida', '234'

contact:
11, 'John', 'Doe', 'generic(at)aol(dot)com'

contact_join:
11, 23, 'region', 'Manager'

There are numerous tables that a record in the contact table might be
connected to which is why I have the parent_table field. If there is a
better way to do this, I'm all ears, but I'd rather my question were answerd
since I dont want to rewrite the code I have already....which leads me to
the question:

I want a view that will show all the relevant information about a region,
namely the regino_name, region_no, c.name_first, c.name_last, c.email and
cj.relationship (contact c, contact_join cj). I have come up with this query
(I'm new at joins if you couldnt guess):

SELECT
r.region_name, r.region_no,
cj.relationship,
c.name_last,
c.name_first,
c.email
FROM
((region r
LEFT JOIN
contact_join cj
ON
((cj.parent_id = r.region_id)))
LEFT JOIN
contact c
ON
((c.id = cj.contact_id)))
WHERE
(cj.parent_table = 'region');

The problem is, sometimes no contact information has been entered yet, and I
need to be able to see regions even if they have no contact information.
The above query will only show items that have a contact_join entry with the
parent_table as 'region'.

In pseudocode, I want this:

SELECT /* region data from region table, and if contact information exists
for a region, select the contact information as well, otherwise leave the
contact fields blank */

Follow? Let me know if this dosent make any sense.

Any help would be appriciated.

Regards
-Tom

---------------------------------
Tom von Schwerdtner
Webmaster, Facilities Plus Inc.
301-340-5101
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