How can foreign key constraints be temporarily disabled using T-SQL?

Question

Are disabling and enabling foreign key constraints supported in SQL Server? Or is my only option to drop and then re-create

Answer 1

I have a more useful version if you are interested. I lifted a bit of code from here a website where the link is no longer active. I modifyied it to allow for an array of tables into the stored procedure and it populates the drop, truncate, add statements before executing all of them. This gives you control to decide which tables need truncating.

/****** Object:  UserDefinedTableType [util].[typ_objects_for_managing]    Script Date: 03/04/2016 16:42:55 ******/
CREATE TYPE [util].[typ_objects_for_managing] AS TABLE(
    [schema] [sysname] NOT NULL,
    [object] [sysname] NOT NULL
)
GO

create procedure [util].[truncate_table_with_constraints]
@objects_for_managing util.typ_objects_for_managing readonly

--@schema sysname
--,@table sysname

as 
--select
--    @table = 'TABLE',
--    @schema = 'SCHEMA'

declare @exec_table as table (ordinal int identity (1,1), statement nvarchar(4000), primary key (ordinal));

--print '/*Drop Foreign Key Statements for ['+@schema+'].['+@table+']*/'

insert into @exec_table (statement)
select
          'ALTER TABLE ['+SCHEMA_NAME(o.schema_id)+'].['+ o.name+'] DROP CONSTRAINT ['+fk.name+']'
from sys.foreign_keys fk
inner join sys.objects o
          on fk.parent_object_id = o.object_id
where 
exists ( 
select * from @objects_for_managing chk 
where 
chk.[schema] = SCHEMA_NAME(o.schema_id)  
and 
chk.[object] = o.name
) 
;
          --o.name = @table and
          --SCHEMA_NAME(o.schema_id)  = @schema

insert into @exec_table (statement) 
select
'TRUNCATE TABLE ' + src.[schema] + '.' + src.[object] 
from @objects_for_managing src
; 

--print '/*Create Foreign Key Statements for ['+@schema+'].['+@table+']*/'
insert into @exec_table (statement)
select 'ALTER TABLE ['+SCHEMA_NAME(o.schema_id)+'].['+o.name+'] ADD CONSTRAINT ['+fk.name+'] FOREIGN KEY (['+c.name+']) 
REFERENCES ['+SCHEMA_NAME(refob.schema_id)+'].['+refob.name+'](['+refcol.name+'])'
from sys.foreign_key_columns fkc
inner join sys.foreign_keys fk
          on fkc.constraint_object_id = fk.object_id
inner join sys.objects o
          on fk.parent_object_id = o.object_id
inner join sys.columns c
          on      fkc.parent_column_id = c.column_id and
                   o.object_id = c.object_id
inner join sys.objects refob
          on fkc.referenced_object_id = refob.object_id
inner join sys.columns refcol
          on fkc.referenced_column_id = refcol.column_id and
                   fkc.referenced_object_id = refcol.object_id
where 
exists ( 
select * from @objects_for_managing chk 
where 
chk.[schema] = SCHEMA_NAME(o.schema_id)  
and 
chk.[object] = o.name
) 
;

          --o.name = @table and
          --SCHEMA_NAME(o.schema_id)  = @schema



declare @looper int , @total_records int, @sql_exec nvarchar(4000)

select @looper = 1, @total_records = count(*) from @exec_table; 

while @looper <= @total_records 
begin

select @sql_exec = (select statement from @exec_table where ordinal =@looper)
exec sp_executesql @sql_exec 
print @sql_exec 
set @looper = @looper + 1
end