sp_fkeys (T-SQL)

Returns logical foreign key information for the current environment. This procedure shows foreign key relationships including disabled foreign keys.

Syntax

sp_fkeys     [@pktable_name =] 'pktable_name'
    [,[@pktable_owner =] 'pktable_owner']
    [,[@pktable_qualifier =] 'pktable_qualifier']
    {, [@fktable_name =] 'fktable_name'}
    [,[@fktable_owner =] 'fktable_owner']
    [,[@fktable_qualifier =] 'fktable_qualifier']

Arguments

[@pktable_name =] 'pktable_name': Is the name of the table (with the primary key) used to return catalog information. pktable_name is sysname, with a default of NULL. Wildcard pattern matching is not supported. This parameter or the fktable_name parameter, or both, must be supplied.
[@pktable_owner =] 'pktable_owner': Is the name of the owner of the table (with the primary key) used to return catalog information. pktable_owner is sysname, with a default of NULL. Wildcard pattern matching is not supported. If pktable_owner is not specified, the default table visibility rules of the underlying DBMS apply.
In Microsoft® SQL Server™, if the current user owns a table with the specified name, that table’s columns are returned. If pktable_owner is not specified and the current user does not own a table with the specified pktable_name, the procedure looks for a table with the specified pktable_name owned by the database owner. If one exists, that table’s columns are returned.
[@pktable_qualifier =] 'pktable_qualifier': Is the name of the table (with the primary key) qualifier. pktable_qualifier is sysname, with a default of NULL. Various DBMS products support three-part naming for tables (qualifier.owner.name). In SQL Server, the qualifier represents the database name. In some products, it represents the server name of the table’s database environment.
[@fktable_name =] 'fktable_name': Is the name of the table (with a foreign key) used to return catalog information. fktable_name is sysname, with a default of NULL. Wildcard pattern matching is not supported. This parameter or the pktable_name parameter, or both, must be supplied.
[@fktable_owner =] 'fktable_owner': Is the name of the owner of the table (with a foreign key) used to return catalog information. fktable_owner is sysname, with a default of NULL. Wildcard pattern matching is not supported. If fktable_owner is not specified, the default table visibility rules of the underlying DBMS apply.
In SQL Server, if the current user owns a table with the specified name, that table’s columns are returned. If fktable_owner is not specified and the current user does not own a table with the specified fktable_name, the procedure looks for a table with the specified fktable_name owned by the database owner. If one exists, that table’s columns are returned.
[@fktable_qualifier =] 'fktable_qualifier': Is the name of the table (with a foreign key) qualifier. fktable_qualifier is sysname, with a default of NULL. In SQL Server, the qualifier represents the database name. In some products, it represents the server name of the table’s database environment.

Return Code Values

None

Result Sets

Column name	Data type	Description
PKTABLE_QUALIFIER	sysname	Name of the table (with the primary key) qualifier. This field can be NULL.
PKTABLE_OWNER	sysname	Name of the table (with the primary key) owner. This field always returns a value.
PKTABLE_NAME	sysname	Name of the table (with the primary key). This field always returns a value.
PKCOLUMN_NAME	sysname	Name of the primary key column(s), for each column of the TABLE_NAME returned. This field always returns a value.
FKTABLE_QUALIFIER	sysname	Name of the table (with a foreign key) qualifier. This field can be NULL.
FKTABLE_OWNER	sysname	Name of the table (with a foreign key) owner. This field always returns a value.
FKTABLE_NAME	sysname	Name of the table (with a foreign key). This field always returns a value.
FKCOLUMN_NAME	varchar(32)	Name of the foreign key column(s), for each column of the TABLE_NAME returned. This field always returns a value.
KEY_SEQ	smallint	Sequence number of the column in a multicolumn primary key. This field always returns a value.
UPDATE_RULE	smallint	Action applied to the foreign key when the SQL operation is an update. SQL Server returns 1 for these columns. Open Data Services gateways can return values of 0, 1, or 2: 0 = CASCADE changes to foreign key. 1 = RESTRICT changes if foreign key is present. 2 = SET_NULL; set foreign key to NULL.
DELETE_RULE	smallint	Action applied to the foreign key when the SQL operation is a deletion. SQL Server returns 1 for these columns. Open Data Services gateways can return values of 0, 1, or 2: 0 = CASCADE changes to foreign key. 1 = RESTRICT changes if foreign key is present. 2 = SET_NULL; set foreign key to NULL.
FK_NAME	sysname	Foreign key identifier. It is NULL if not applicable to the data source. SQL Server returns the FOREIGN KEY constraint name.
PK_NAME	sysname	Primary key identifier. It is NULL if not applicable to the data source. SQL Server returns the PRIMARY KEY constraint name.

The results returned are ordered by FKTABLE_QUALIFIER, FKTABLE_OWNER, FKTABLE_NAME, and KEY_SEQ.

Remarks

Application coding that includes tables with disabled foreign keys can be implemented by:

Temporarily disabling constraint checking (ALTER TABLE NOCHECK or CREATE TABLE NOT FOR REPLICATION) while working with the tables, and enabling it again later.
Using triggers or application code to enforce relationships.

If the primary key table name is supplied and the foreign key table name is NULL, sp_fkeys returns all tables that include a foreign key to the given table. If the foreign key table name is supplied and the primary key table name is NULL, sp_fkeys returns all tables related by a primary key/foreign key relationship to foreign keys in the foreign key table. Note that this procedure does not support the common key type as specified in the SQL Server syskeys system table.

The sp_fkeys stored procedure is equivalent to SQLForeignKeys in ODBC.

Permissions

Execute permissions default to the public role.

Examples

This example retrieves a list of foreign keys for the Customers table in the Northwind database.

USE Northwind

EXEC sp_fkeys @pktable_name = N'Customers'