asked on An ERM and a complex recursive relation
Hi experts
I'm at my witt's end and hope you can help me.
In my ERM I have an entity "user" which has a recursive relation.
-------------
a user can also have one or none substitute user, while a subtitute user can substitute (n) users.
like:
user --1-------- substitutes -------- mc -- user
user --1 ------- has substitute user --------- c -- user
-------------
and a user (or subsitute user) can have (n) threads
user -- 1 -------------------- mc -- threads
I tried many things, but I'm not sure how to transform this relations into a valid ERM.
The Problem is I need to be able to tell if a substitute user or a normal user owns a certain thread.
I'm very thankful for any help :)
I'm at my witt's end and hope you can help me.
In my ERM I have an entity "user" which has a recursive relation.
-------------
a user can also have one or none substitute user, while a subtitute user can substitute (n) users.
like:
user --1-------- substitutes -------- mc -- user
user --1 ------- has substitute user --------- c -- user
-------------
and a user (or subsitute user) can have (n) threads
user -- 1 -------------------- mc -- threads
I tried many things, but I'm not sure how to transform this relations into a valid ERM.
The Problem is I need to be able to tell if a substitute user or a normal user owns a certain thread.
I'm very thankful for any help :)
DatabasesMicrosoft SQL Server 2005
Last Comment
Arikael
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ASKER
Hi
I just gave your solution an other look, I think I was wrong when I said, your solution wouldn't work.
But to make it work I would have to create the relation between users and threads with the field ManagerID (in your example)
Which would result in redundant data, I guess.
I just gave your solution an other look, I think I was wrong when I said, your solution wouldn't work.
But to make it work I would have to create the relation between users and threads with the field ManagerID (in your example)
Which would result in redundant data, I guess.
I think I didn't explain the thing with the threads correctly.
Whenever a user creates/owns a thread, I need to be able to tell if a normal user or a substitute user owns the thread. But when a substitute user owns a thread I also need to know which user he substitutes.
I think this is the part where I struggle.
With your solution this doesn't seem possible (or am I wrong?)