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Thursday, January 17, 2008

Find all the foreign keys in a database

I am getting so many mails and msgs from new bees on how to find out the relationship between the tables to understand the tables in better way. After spending good amount finally came up with the query to get this info.



SELECT
FK_Table = FK.TABLE_NAME,
FK_Column = CU.COLUMN_NAME,
PK_Table = PK.TABLE_NAME,
PK_Column = PT.COLUMN_NAME,
Constraint_Name = C.CONSTRAINT_NAME
FROM
INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS C
INNER JOIN
INFORMATION_SCHEMA.TABLE_CONSTRAINTS FK
ON C.CONSTRAINT_NAME = FK.CONSTRAINT_NAME
INNER JOIN
INFORMATION_SCHEMA.TABLE_CONSTRAINTS PK
ON C.UNIQUE_CONSTRAINT_NAME = PK.CONSTRAINT_NAME
INNER JOIN
INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU
ON C.CONSTRAINT_NAME = CU.CONSTRAINT_NAME
INNER JOIN
(
SELECT
i1.TABLE_NAME, i2.COLUMN_NAME
FROM
INFORMATION_SCHEMA.TABLE_CONSTRAINTS i1
INNER JOIN
INFORMATION_SCHEMA.KEY_COLUMN_USAGE i2
ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME
WHERE i1.CONSTRAINT_TYPE = 'PRIMARY KEY'
) PT
ON PT.TABLE_NAME = PK.TABLE_NAME
-- optional:
ORDER BY
1,2,3,4

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