Re: Help for advanced SQL query

From: gene <usenet_at_smalltime.com>
Date: 31 May 2001 14:44:52 -0700
Message-ID: <9a95c0dd.0105311344.35eed2b7@posting.google.com>

"Randall Roberts" <randall_at_filer.org.nospam> wrote in message news:<3b13099e_1_at_news.pcmagic.net>...
> Yes, as Daniel said, you have to resolve a many to many relationship with a
> third table, which he and I call an intersection entity... but which I've
> heard called a "join table", "resolution table", and a couple of other
> things in my career.
>

Thanks for your replies. There actually is a third table (alluded to by the cluster_ids), though it seems different from the third table that you're describing. Here is a simplified description of the tables:  

 table OBJECT

---

 object_id (PK)
 name
 cluster_id (FK)  

 table MAP

---

 map_id (PK)
 position
 source
 cluster_id (FK)  

 table CLUSTER

---

 cluster_id (PK)
 name

If I were to create an additional table directly relating the maps and the objects:

 table OBJECT_MAP

---

 map_id (FK)
 object_id (FK)

it would just be the same product of the two tables as I get by doing the join, or am I missing something? Received on Thu May 31 2001 - 16:44:52 CDT