Technical Article

Effectively mapping primary key – foreign key relations

,

To properly locating the primary key - foreign key relations in a database sounds like a tough task. Mohit Nayyar posted a technique to find out primary key and foreign key that have the same column names. The limitation of that is that, in reality, column names are not always the same in a database. For example, in the AdvantureWorks sample database in SQL2005, the SalesPersonID in Sales.SalesPerson table has a foreign key reference to the EmployeeID column in the HumanResources.Employee table.

This script will map the primary key and foreign key, regardless if the column names are same or not. This script has been tested on both SQL2000 and 2005. This is another evidence of the usefulness of the information_schema view.

If you are interest in a particular column, simple add " and ccu.column_name='<column name>'" in the where cluse.

Mohit's Column: http://www.sqlservercentral.com/scripts/Miscellaneous/31983/

By John Liu, 2007/11/07

select 'PK_Table_Schema'=ccu.table_schema,'PK_Table_Name'=ccu.table_name,'PK_Column_Name'=ccu.column_name,'PK_Constraint_Name'=ccu.constraint_name, 
'FK_Table_Schema'=ccu1.table_schema,'FK_Table_Name'=ccu1.table_name, 'FK_Column_Name'=ccu1.column_name, 
'FK_Constraint_Name'=rc.constraint_name 
from information_schema.constraint_column_usage CCU inner join information_schema.referential_constraints RC
on CCU.constraint_name=RC.unique_constraint_name
inner join information_schema.constraint_column_usage CCU1 on RC.constraint_name=ccu1.constraint_name
where ccu.constraint_name not in (select constraint_name from information_schema.referential_constraints)

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