How to make a foreign key in sql server

Question

I have a table in which i am making two columns as a combine as primary key i think this is called a composit key , Now in another table i want to make one of these two columns as foreign key when i tried that it gives an error , i think it is saying that i should include both columns from second table as well , check the link for table structure

https://sweet-gmail.tinytake.com/sf/NzgwNjE0XzM1MTM1OTk

Vinay Singh · Answer

Hi This may help you As we know Table2 has a composite primary key (FileID FileType)  then any reference to it must also include both columns . ALTER TABLE dbo. Table1 ADD CONSTRAINT FK_Table1_Table2 FOREIGN KEY(FileID FileType) REFERENCES Table2(FileID FileType) For detail check the link http://stackoverflow.com/questions/7650969/foreign-key-used-in-composite-primary-key

barathi raja · Answer

Examples with Primary key and Reference Tables for Foreign Key: /* Primary Key*/ create table prim(id intname varchar(30)constraint p_id PRIMARY KEY(Id)) select * from prim insert into prim(idname) values(12'hari') insert into prim(idname) values(12'soori') /* Foreign Key*/ create table foregn(f_id intmail varchar(20)constraint f_id foreign key(f_id) references prim(Id)) select * from foregn select * from tbl_student

Karthik Elumalai · Answer

Hi Mark tabor Yup as vinay singh said we need to refer both the columns for the foreign key kindly the below link for detailed info: http://searchoracle.techtarget.com/answer/Foreign-key-referencing-only-part-of-composite-primary-key kindly let me know your thoughts thanks karthik

Balamurali Krishnan R · Answer

use the following script ALTER TABLE dbo.Childtable ADD CONSTRAINT FK_Childtable_ParentTable FOREIGN KEY(OrderId CompanyId) REFERENCES dbo.ParentTable(OrderId CompanyId)