can foreign key field have a unique value

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SQL-Server-2008

i have one table having one primary key

create table PSM.dbo.Prospect(Prospect_ID int primary key,Prospect_Name varchar(50),Prospect_Source varchar(50),Prospect_Products_Services varchar(50) );

2nd table having foreign key and one primary key

create table PSM.dbo.conversion(Prospect_ID int references Prospect(Prospect_ID)  ,Customer_ID int primary key,Customer_Name varchar(50),Customer_Products_Services varchar(50));

now i want 2nd table having propect_id should also have unique value(no duplication).so hw can i do this

Posted 5-May-11 21:07pm

shivani 2013

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Sandeep Mewara · Answer 1 · 2011-05-05T21:12:00

Put a unique constraint on that field of the 2nd table. Thus, even though it will be a Foreign Key, the constraint will make sure that no duplication happens at the time of insertion. Any repeat would throw a constraint error.

Read here:
http://msdn.microsoft.com/en-us/library/ms191166.aspx[^]
http://msdn.microsoft.com/en-us/library/aa933091%28v=sql.80%29.aspx[^]
http://www.w3schools.com/sql/sql_unique.asp[^]

Ra-one · Answer 2 · 2011-05-05T23:00:00

Solution 2

Add a Unique key to it

SQL

ALTER TABLE PSM.dbo.conversion
ADD UNIQUE (propect_id)

Hope it helps.......

Posted 5-May-11 23:00pm

Ra-one

Updated 5-May-11 23:46pm

v3