By: Greg Robidoux | Comments (4) | Related: 1 | 2 | 3 | 4 | 5 | > Constraints
Problem
SQL Server Enterprise Manager and Management Studio are pretty good tools for giving you information about a particular object, but when you want to get information across your entire database or server this becomes a bit of a challenge. There are several system stored procedures and now dynamic management views in SQL Server to provide some of the information, but there is still a bit of missing functionality if you want to get data across the database or server. One of these recent challenges was getting foreign key information across the entire database. Management Studio has some nice additions where you can see the FK constraints on a table by table basis, but getting all of the foreign keys is a bit more a challenge. There is a stored procedure called sp_fkeys, but this procedure requires you to include at least the primary key table name. So how can you get a complete list?
Solution
There is a wealth of information in the system stored procedures and this is another good way of learning how things work behind the scenes. By taking a look at the stored procedure sp_fkeys for SQL Server I noticed that it is not very complicated at all. When you pass in the parameters it basically uses the parameters to filter your selection. By making a minor tweak to the SELECT statement we are able to get a list of all FKs in the entire database. Here is the modified query for SQL Server 2005 and later.
SQL Server List Foreign Keys - Version 1
SELECT PKTABLE_QUALIFIER = CONVERT(SYSNAME,DB_NAME()),
PKTABLE_OWNER = CONVERT(SYSNAME,SCHEMA_NAME(O1.SCHEMA_ID)),
PKTABLE_NAME = CONVERT(SYSNAME,O1.NAME),
PKCOLUMN_NAME = CONVERT(SYSNAME,C1.NAME),
FKTABLE_QUALIFIER = CONVERT(SYSNAME,DB_NAME()),
FKTABLE_OWNER = CONVERT(SYSNAME,SCHEMA_NAME(O2.SCHEMA_ID)),
FKTABLE_NAME = CONVERT(SYSNAME,O2.NAME),
FKCOLUMN_NAME = CONVERT(SYSNAME,C2.NAME),
-- Force the column to be non-nullable (see SQL BU 325751)
--KEY_SEQ = isnull(convert(smallint,k.constraint_column_id), sysconv(smallint,0)),
UPDATE_RULE = CONVERT(SMALLINT,CASE OBJECTPROPERTY(F.OBJECT_ID,'CnstIsUpdateCascade')
WHEN 1 THEN 0
ELSE 1
END),
DELETE_RULE = CONVERT(SMALLINT,CASE OBJECTPROPERTY(F.OBJECT_ID,'CnstIsDeleteCascade')
WHEN 1 THEN 0
ELSE 1
END),
FK_NAME = CONVERT(SYSNAME,OBJECT_NAME(F.OBJECT_ID)),
PK_NAME = CONVERT(SYSNAME,I.NAME),
DEFERRABILITY = CONVERT(SMALLINT,7) -- SQL_NOT_DEFERRABLE
FROM SYS.ALL_OBJECTS O1,
SYS.ALL_OBJECTS O2,
SYS.ALL_COLUMNS C1,
SYS.ALL_COLUMNS C2,
SYS.FOREIGN_KEYS F
INNER JOIN SYS.FOREIGN_KEY_COLUMNS K
ON (K.CONSTRAINT_OBJECT_ID = F.OBJECT_ID)
INNER JOIN SYS.INDEXES I
ON (F.REFERENCED_OBJECT_ID = I.OBJECT_ID
AND F.KEY_INDEX_ID = I.INDEX_ID)
WHERE O1.OBJECT_ID = F.REFERENCED_OBJECT_ID
AND O2.OBJECT_ID = F.PARENT_OBJECT_ID
AND C1.OBJECT_ID = F.REFERENCED_OBJECT_ID
AND C2.OBJECT_ID = F.PARENT_OBJECT_ID
AND C1.COLUMN_ID = K.REFERENCED_COLUMN_ID
AND C2.COLUMN_ID = K.PARENT_COLUMN_ID
SQL Server List Foreign Keys - Version 2
This is another version that was contributed by one of our readers Troy Ketsdever. This uses the INFORMATION_SCHEMA views.
SELECT C.TABLE_CATALOG [PKTABLE_QUALIFIER],
C.TABLE_SCHEMA [PKTABLE_OWNER],
C.TABLE_NAME [PKTABLE_NAME],
KCU.COLUMN_NAME [PKCOLUMN_NAME],
C2.TABLE_CATALOG [FKTABLE_QUALIFIER],
C2.TABLE_SCHEMA [FKTABLE_OWNER],
C2.TABLE_NAME [FKTABLE_NAME],
KCU2.COLUMN_NAME [FKCOLUMN_NAME],
RC.UPDATE_RULE,
RC.DELETE_RULE,
C.CONSTRAINT_NAME [FK_NAME],
C2.CONSTRAINT_NAME [PK_NAME],
CAST(7 AS SMALLINT) [DEFERRABILITY]
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS C
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE KCU
ON C.CONSTRAINT_SCHEMA = KCU.CONSTRAINT_SCHEMA
AND C.CONSTRAINT_NAME = KCU.CONSTRAINT_NAME
INNER JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS RC
ON C.CONSTRAINT_SCHEMA = RC.CONSTRAINT_SCHEMA
AND C.CONSTRAINT_NAME = RC.CONSTRAINT_NAME
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS C2
ON RC.UNIQUE_CONSTRAINT_SCHEMA = C2.CONSTRAINT_SCHEMA
AND RC.UNIQUE_CONSTRAINT_NAME = C2.CONSTRAINT_NAME
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE KCU2
ON C2.CONSTRAINT_SCHEMA = KCU2.CONSTRAINT_SCHEMA
AND C2.CONSTRAINT_NAME = KCU2.CONSTRAINT_NAME
AND KCU.ORDINAL_POSITION = KCU2.ORDINAL_POSITION
WHERE C.CONSTRAINT_TYPE = 'FOREIGN KEY'
SQL Server 2000 Version
With SQL Server 2000 it is not as straight forward as using a simple SQL statement as shown above. In order to get this to work for SQL Server 2000 an adjustment was made to the sp_fkeys SP to cursor through all of the user tables. It is not the prettiest method, but it does seem to do the job.
click here for the SQL 2000 version script
Next Steps
- Add these scripts to your toolbox and next time you are doing some investigative work on your severs use these to get an idea of what FKs exist in your databases.
- Take a look at these other tips to help gather information about your server or databases
About the author
Greg Robidoux is the President and founder of Edgewood Solutions, a technology services company delivering services and solutions for Microsoft SQL Server. He is also one of the co-founders of MSSQLTips.com. Greg has been working with SQL Server since 1999, has authored numerous database-related articles, and delivered several presentations related to SQL Server. Before SQL Server, he worked on many data platforms such as DB2, Oracle, Sybase, and Informix.This author pledges the content of this article is based on professional experience and not AI generated.
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