How can I retrieve foreign key references using SQL Server's INFORMATION_SCHEMA?

Getting Foreign Key References from Information_Schema in SQL Server

In SQL Server, foreign keys play a crucial role in maintaining referential integrity within a database. To retrieve information about foreign key references, the information_schema can be a valuable resource.

Query to Retrieve Foreign Key References:

The following query retrieves the foreign key constraint name, referenced table, and column for a given foreign key column:

SELECT 
     KCU1.CONSTRAINT_SCHEMA AS FK_CONSTRAINT_SCHEMA 
    ,KCU1.CONSTRAINT_NAME AS FK_CONSTRAINT_NAME 
    ,KCU1.TABLE_SCHEMA AS FK_TABLE_SCHEMA 
    ,KCU1.TABLE_NAME AS FK_TABLE_NAME 
    ,KCU1.COLUMN_NAME AS FK_COLUMN_NAME 
    ,KCU2.TABLE_SCHEMA AS REFERENCED_TABLE_SCHEMA 
    ,KCU2.TABLE_NAME AS REFERENCED_TABLE_NAME 
    ,KCU2.COLUMN_NAME AS REFERENCED_COLUMN_NAME 
FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS AS RC 

INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KCU1 
    ON KCU1.CONSTRAINT_CATALOG = RC.CONSTRAINT_CATALOG  
    AND KCU1.CONSTRAINT_SCHEMA = RC.CONSTRAINT_SCHEMA 
    AND KCU1.CONSTRAINT_NAME = RC.CONSTRAINT_NAME 

INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KCU2 
    ON KCU2.CONSTRAINT_CATALOG = RC.UNIQUE_CONSTRAINT_CATALOG  
    AND KCU2.CONSTRAINT_SCHEMA = RC.UNIQUE_CONSTRAINT_SCHEMA 
    AND KCU2.CONSTRAINT_NAME = RC.UNIQUE_CONSTRAINT_NAME 
    AND KCU2.ORDINAL_POSITION = KCU1.ORDINAL_POSITION 

Note: Information_schema does not contain indices. To find foreign keys based on unique indices, refer to the proprietary tables of SQL Server.

Example of Foreign Key Reference Retrieval:

Consider the following table structure:

CREATE TABLE [dbo].[T_ALV_Ref_FilterDisplay] (
    [FA_MDT_ID] [varchar](20) NOT NULL,
    [FA_NAME] [varchar](255) NOT NULL
)

CREATE TABLE [dbo].[T_AP_Ref_Customer] (
    [MDT_ID] [varchar](20) NOT NULL,
    [CUST_NAME] [varchar](255) NOT NULL
)

ALTER TABLE [dbo].[T_ALV_Ref_FilterDisplay]  WITH CHECK ADD  CONSTRAINT [FK_T_ALV_Ref_FilterDisplay_T_AP_Ref_Customer] FOREIGN KEY([FA_MDT_ID])
REFERENCES [dbo].[T_AP_Ref_Customer] ([MDT_ID])

To retrieve the referenced table and column for the foreign key [FA_MDT_ID], execute the following query:

SELECT 
     FK_TABLE_NAME, 
     REFERENCED_TABLE_NAME, 
     REFERENCED_COLUMN_NAME 
FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS 
WHERE FK_TABLE_NAME = 'T_ALV_Ref_FilterDisplay' 
  AND FK_COLUMN_NAME = 'FA_MDT_ID'

The result will display:

FK_TABLE_NAME | REFERENCED_TABLE_NAME | REFERENCED_COLUMN_NAME
---------------|----------------------|-------------------------
T_ALV_Ref_FilterDisplay | T_AP_Ref_Customer    | MDT_ID

This indicates that the foreign key [FA_MDT_ID] in [T_ALV_Ref_FilterDisplay] refers to the [MDT_ID] column in the [T_AP_Ref_Customer] table.

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