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 a data modeling question
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itmaster
Starting Member

16 Posts

Posted - 09/10/2013 :  19:41:24  Show Profile  Reply with Quote
Hi,
Can someone please tell me if I have this right.
I have always been taught that you can connect two table if the have a 1 to many relation ship. However, if you have a Many to many relation ship you cannot connect them. In this case you need an intersection table put between them. I have seen though people doing this even though the first two table form a one to many relation ship.
Is there a circumstance where you would do this, without having a many to many relationship.

thank you

Edited by - itmaster on 09/10/2013 19:41:54

itmaster
Starting Member

16 Posts

Posted - 09/11/2013 :  11:36:51  Show Profile  Reply with Quote
Maybe I put this in the wrong forum? Can it be moved to Database Design and Application Architecture?
Thank you
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visakh16
Very Important crosS Applying yaK Herder

India
52309 Posts

Posted - 09/12/2013 :  16:39:23  Show Profile  Reply with Quote
you may need a intermediate table in one to many relationships when many part table will have some attributes which is not dependent on each instance of relationship and just depends on its key. In that case to avoid redundancy in repeating values for all those related attributes, you apply normailsation and seperate them out into a its own master table and you will just have relationship in a intermediate table with just the keys from participating tables and any attributes which stands unique for each of the relationship.

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/
https://www.facebook.com/VmBlogs
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itmasterw
Yak Posting Veteran

90 Posts

Posted - 09/16/2013 :  13:17:22  Show Profile  Reply with Quote
quote:
Originally posted by visakh16

you may need a intermediate table in one to many relationships when many part table will have some attributes which is not dependent on each instance of relationship and just depends on its key. In that case to avoid redundancy in repeating values for all those related attributes, you apply normailsation and seperate them out into a its own master table and you will just have relationship in a intermediate table with just the keys from participating tables and any attributes which stands unique for each of the relationship.

------------------------------------------------------------------------------------------------------

Thank you
SQL Server MVP
http://visakhm.blogspot.com/
https://www.facebook.com/VmBlogs




ITM
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