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

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 tabl

Answer 1

The following solution work for me:

--Eliminar las llaves foraneas
declare @query varchar(8000)
declare cursorRecorrerTabla cursor for

SELECT  'ALTER TABLE [PoaComFinH].['+sch.name+'].['+referencingTable.Name+'] DROP CONSTRAINT ['+foreignKey.name+']' 'query'
FROM PoaComFinH.sys.foreign_key_columns fk
JOIN PoaComFinH.sys.tables referencingTable ON fk.parent_object_id = referencingTable.object_id
JOIN PoaComFinH.sys.schemas sch ON referencingTable.schema_id = sch.schema_id
JOIN PoaComFinH.sys.objects foreignKey ON foreignKey.object_id = fk.constraint_object_id
JOIN PoaComFinH.sys.tables referencedTable ON fk.referenced_object_id = referencedTable.object_id


--3ro. abrir el cursor.
open cursorRecorrerTabla
fetch next from cursorRecorrerTabla
into @query
while @@fetch_status = 0
begin
--inicio cuerpo del cursor
    print @query
    exec(@query)
--fin cuerpo del cursor
fetch next from cursorRecorrerTabla
into @query
end
--cerrar cursor
close cursorRecorrerTabla
deallocate cursorRecorrerTabla

Answer 2

There is how to get count of all responsibilities for selected Id. Just change @dbTableName value, @dbRowId value and its type (if int you need to remove '' in line no 82 (..SET @SQL = ..)). Enjoy.

DECLARE @dbTableName varchar(max) = 'User'
DECLARE @dbRowId uniqueidentifier = '21d34ecd-c1fd-11e2-8545-002219a42e1c'

DECLARE @FK_ROWCOUNT int
DECLARE @SQL nvarchar(max)

DECLARE @PKTABLE_QUALIFIER sysname
DECLARE @PKTABLE_OWNER sysname
DECLARE @PKTABLE_NAME sysname
DECLARE @PKCOLUMN_NAME sysname
DECLARE @FKTABLE_QUALIFIER sysname
DECLARE @FKTABLE_OWNER sysname
DECLARE @FKTABLE_NAME sysname
DECLARE @FKCOLUMN_NAME sysname
DECLARE @UPDATE_RULE smallint
DECLARE @DELETE_RULE smallint
DECLARE @FK_NAME sysname
DECLARE @PK_NAME sysname
DECLARE @DEFERRABILITY sysname

IF OBJECT_ID('tempdb..#Temp1') IS NOT NULL
    DROP TABLE #Temp1;
CREATE TABLE #Temp1 ( 
    PKTABLE_QUALIFIER sysname,
    PKTABLE_OWNER sysname,
    PKTABLE_NAME sysname,
    PKCOLUMN_NAME sysname,
    FKTABLE_QUALIFIER sysname,
    FKTABLE_OWNER sysname,
    FKTABLE_NAME sysname,
    FKCOLUMN_NAME sysname,
    UPDATE_RULE smallint,
    DELETE_RULE smallint,
    FK_NAME sysname,
    PK_NAME sysname,
    DEFERRABILITY sysname,
    FK_ROWCOUNT int
    );
DECLARE FK_Counter_Cursor CURSOR FOR
    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
           AND O1.NAME = @dbTableName
OPEN FK_Counter_Cursor;
FETCH NEXT FROM FK_Counter_Cursor INTO @PKTABLE_QUALIFIER, @PKTABLE_OWNER, @PKTABLE_NAME, @PKCOLUMN_NAME, @FKTABLE_QUALIFIER, @FKTABLE_OWNER, @FKTABLE_NAME, @FKCOLUMN_NAME, @UPDATE_RULE, @DELETE_RULE, @FK_NAME, @PK_NAME, @DEFERRABILITY;
WHILE @@FETCH_STATUS = 0
   BEGIN
        SET @SQL = 'SELECT @dbCountOut = COUNT(*) FROM [' + @FKTABLE_NAME + '] WHERE [' + @FKCOLUMN_NAME + '] = ''' + CAST(@dbRowId AS varchar(max)) + '''';
        EXECUTE sp_executesql @SQL, N'@dbCountOut int OUTPUT', @dbCountOut = @FK_ROWCOUNT OUTPUT;
        INSERT INTO #Temp1 (PKTABLE_QUALIFIER, PKTABLE_OWNER, PKTABLE_NAME, PKCOLUMN_NAME, FKTABLE_QUALIFIER, FKTABLE_OWNER, FKTABLE_NAME, FKCOLUMN_NAME, UPDATE_RULE, DELETE_RULE, FK_NAME, PK_NAME, DEFERRABILITY, FK_ROWCOUNT) VALUES (@FKTABLE_QUALIFIER, @PKTABLE_OWNER, @PKTABLE_NAME, @PKCOLUMN_NAME, @FKTABLE_QUALIFIER, @FKTABLE_OWNER, @FKTABLE_NAME, @FKCOLUMN_NAME, @UPDATE_RULE, @DELETE_RULE, @FK_NAME, @PK_NAME, @DEFERRABILITY, @FK_ROWCOUNT)
      FETCH NEXT FROM FK_Counter_Cursor INTO @PKTABLE_QUALIFIER, @PKTABLE_OWNER, @PKTABLE_NAME, @PKCOLUMN_NAME, @FKTABLE_QUALIFIER, @FKTABLE_OWNER, @FKTABLE_NAME, @FKCOLUMN_NAME, @UPDATE_RULE, @DELETE_RULE, @FK_NAME, @PK_NAME, @DEFERRABILITY;
   END;
CLOSE FK_Counter_Cursor;
DEALLOCATE FK_Counter_Cursor;
GO
SELECT * FROM #Temp1
GO