How can I list all foreign keys referencing a given table in SQL Server? – Dev

The best answers to the question “How can I list all foreign keys referencing a given table in SQL Server?” in the category Dev.

QUESTION:

I need to remove a highly referenced table in a SQL Server database. How can I get a list of all the foreign key constraints I will need to remove in order to drop the table?

(SQL answers preferable over clicking about in the GUI of the management studio.)

ANSWER:

I’d use the Database Diagramming feature in SQL Server Management Studio, but since you ruled that out – this worked for me in SQL Server 2008 (don’t have 2005).

To get list of referring table and column names…

select 
    t.name as TableWithForeignKey, 
    fk.constraint_column_id as FK_PartNo, c.
    name as ForeignKeyColumn 
from 
    sys.foreign_key_columns as fk
inner join 
    sys.tables as t on fk.parent_object_id = t.object_id
inner join 
    sys.columns as c on fk.parent_object_id = c.object_id and fk.parent_column_id = c.column_id
where 
    fk.referenced_object_id = (select object_id 
                               from sys.tables 
                               where name="TableOthersForeignKeyInto")
order by 
    TableWithForeignKey, FK_PartNo

To get names of foreign key constraints

select distinct name from sys.objects where object_id in 
(   select fk.constraint_object_id from sys.foreign_key_columns as fk
    where fk.referenced_object_id = 
        (select object_id from sys.tables where name="TableOthersForeignKeyInto")
)

ANSWER:

Not sure why no one suggested but I use sp_fkeys to query foreign keys for a given table:

EXEC sp_fkeys 'TableName'

You can also specify the schema:

EXEC sp_fkeys @pktable_name="TableName", @pktable_owner="dbo"

Without specifying the schema, the docs state the following:

If pktable_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 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.

ANSWER:

Try this :

sp_help 'TableName'

ANSWER:

This gives you:

  • The FK itself itself
  • Schema that the FK belongs to
  • The “referencing table” or the table that has the FK
  • The “referencing column” or the column inside referencing table that points to the FK
  • The “referenced table” or the table that has the key column that your FK is pointing to
  • The “referenced column” or the column that is the key that your FK is pointing to

Code below:

SELECT  obj.name AS FK_NAME,
    sch.name AS [schema_name],
    tab1.name AS [table],
    col1.name AS [column],
    tab2.name AS [referenced_table],
    col2.name AS [referenced_column]
FROM sys.foreign_key_columns fkc
INNER JOIN sys.objects obj
    ON obj.object_id = fkc.constraint_object_id
INNER JOIN sys.tables tab1
    ON tab1.object_id = fkc.parent_object_id
INNER JOIN sys.schemas sch
    ON tab1.schema_id = sch.schema_id
INNER JOIN sys.columns col1
    ON col1.column_id = parent_column_id AND col1.object_id = tab1.object_id
INNER JOIN sys.tables tab2
    ON tab2.object_id = fkc.referenced_object_id
INNER JOIN sys.columns col2
    ON col2.column_id = referenced_column_id AND col2.object_id = tab2.object_id