composite primary key and foreign key

I refer a composite primary key of a master table, I have to refer all the fields of the composite primary key. But how to partially refer the composite primary key in a child table? For example, if PARENT table  has primary key (A,B,C), how to create a foreign key in CHILD table which will refer only (A,B) fields of Table1?

 

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laknath27
3/26/2009 7:44:48 AM
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Hi,

Please refer to the following description:

MSDN:

In a foreign key reference, a link is created between two tables when the column or columns that hold the primary key value for one table are referenced by the column or columns in another table. This column becomes a foreign key in the second table.

If the primary key for PARENT table is a composite primary key (A, B, C), the foreign key should also be (A, B, C). (A, B) is not the primary key for PARENT table.

If we would like to make the primary key short, we can create another ID column in PARENT table (ID, A, B, C …), e.g. an auto-increase identity column. After that, we specify the ID as primary key and create the foreign key reference.

Related links:

http://social.msdn.microsoft.com/Forums/en-US/transactsql/thread/158d77f7-3029-43bc-bba6-a8a12374f00c/

FOREIGN KEY Constraints
http://msdn.microsoft.com/en-us/library/ms175464.aspx


 


Jian Kang
Microsoft Online Community Support

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
0
Jian
3/31/2009 7:46:45 AM

U r saying that in Parent table primary  key was defined on the columns A,B,C. If u want to define a foreign key in child table u need the columns A,B,C. U cannot define on the columns A,B. One of the solution is mentioned by Jian Kang . I prefer to follow the same solution.


Thank u

Baba

Please remember to click "Mark as Answer" on this post if it helped you.
0
srijaya_ramaraju
3/31/2009 9:32:54 AM

U r saying that in Parent table primary  key was defined on the columns A,B,C. If u want to define a foreign key in child table u need the columns A,B,C. U cannot define on the columns A,B. One of the solution is mentioned by Jian Kang . I prefer to follow the same solution.


Thank u

Baba

Please remember to click "Mark as Answer" on this post if it helped you.
0
srijaya_ramaraju
3/31/2009 10:04:36 AM
Reply:

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