SQL Script to alter ALL Foreign Keys to add ON DELETE CASCADE

Question

I have a SQL 2005 database with approx 250 tables.

I want to temporarily enable ON DELETE CASCADE to all of the Foreign Keys so that I can do a bulk delete easily.

Answer 1

The answer from @Andomar worked for me but it was a bit manual - you have to run it, then copy the results and run them. I needed to use this as part of my automated test setup so needed it to run in one query automatically.

I have come up with the following which gets all the SQL to run in order to modify the foreign key constraints, then actually runs it all in one go:

    IF Object_id('tempdb..#queriesForContraints') IS NOT NULL 
      BEGIN 
          DROP TABLE #queriesForContraints
      END 

    DECLARE @ignoreTablesCommaSeparated VARCHAR(1000)

    SELECT 'ALTER TABLE [' 
           + ForeignKeys.foreigntableschema + '].[' 
           + ForeignKeys.foreigntablename 
           + '] DROP CONSTRAINT [' 
           + ForeignKeys.foreignkeyname + ']; ' 
           + 'ALTER TABLE [' 
           + ForeignKeys.foreigntableschema + '].[' 
           + ForeignKeys.foreigntablename 
           + '] WITH CHECK ADD CONSTRAINT [' 
           + ForeignKeys.foreignkeyname 
           + '] FOREIGN KEY([' 
           + ForeignKeys.foreigntablecolumn 
           + ']) REFERENCES [' 
           + Schema_name(sys.objects.schema_id) + '].[' 
           + sys.objects.[name] + ']([' 
           + sys.columns.[name] 
           + ']) ON DELETE CASCADE; ' AS query
    INTO #queriesForContraints
    FROM   sys.objects 
           INNER JOIN sys.columns 
                   ON ( sys.columns.[object_id] = sys.objects.[object_id] ) 
           INNER JOIN (SELECT sys.foreign_keys.[name]                      AS 
                              ForeignKeyName, 
                              Schema_name(sys.objects.schema_id)           AS 
                  ForeignTableSchema, 
                              sys.objects.[name]                           AS 
                  ForeignTableName, 
                              sys.columns.[name]                           AS 
                  ForeignTableColumn, 
                              sys.foreign_keys.referenced_object_id        AS 
                  referenced_object_id, 
                              sys.foreign_key_columns.referenced_column_id AS 
                  referenced_column_id 
                       FROM   sys.foreign_keys 
                              INNER JOIN sys.foreign_key_columns 
                                      ON ( 
                              sys.foreign_key_columns.constraint_object_id = 
                              sys.foreign_keys.[object_id] ) 
                              INNER JOIN sys.objects 
                                      ON ( sys.objects.[object_id] = 
                                         sys.foreign_keys.parent_object_id ) 
                              INNER JOIN sys.columns 
                                      ON ( sys.columns.[object_id] = 
                                           sys.objects.[object_id] ) 
                                         AND ( sys.columns.column_id = 
    sys.foreign_key_columns.parent_column_id )) 
    ForeignKeys 
    ON ( ForeignKeys.referenced_object_id = sys.objects.[object_id] ) 
    AND ( ForeignKeys.referenced_column_id = sys.columns.column_id ) 
    WHERE  ( sys.objects.[type] = 'U' ) 
           AND ( sys.objects.[name] NOT IN ( 
                'sysdiagrams' --add more comma separated table names here if required
            ) ) 

    DECLARE @queryToRun NVARCHAR(MAX)

    SELECT  @queryToRun = STUFF(
            (SELECT query + ''
             FROM #queriesForContraints
             FOR XML PATH (''))
         , 1, 0, '')

    EXEC sp_executesql @statement = @queryToRun

    IF Object_id('tempdb..#queriesForContraints') IS NOT NULL 
      BEGIN 
          DROP TABLE #queriesForContraints
      END