Truncate All Tables

,

This is the part 1 of 2.

Script to removed all the constraints from a database to truncate all the tables.

Most of the time this approach is used to deleted all records from a database or set staging

tables from an existing database model.

How to used:

1.- Create table to hold constraints values ( part 2 explain how to revert the process)

2.-Populate table

3.- Create cursor to remove constraints

4.- truncate all data

 

 

Use DatabaseName --Temporary table to hold constraints info most of the time at a different location 
                 -- or database
--This could be a temp table however set as static 

IF  EXISTS (Select [name] from sys.tables where [name] = 'T_FK_Xref' and type = 'U') 
 truncate table T_FK_Xref
go
--Create Table to store constraint information
 IF  NOT EXISTS  (Select [name] from sys.tables where [name] = 'T_FK_Xref' and type = 'U')
 Create table DatabaseName.dbo.T_FK_Xref (
 ID int identity (1,1),
 ConstraintName varchar (255),
 MasterTable varchar(255),
 MasterColumn varchar(255),
 ChildTable varchar(255),
 ChildColumn varchar(255),
 FKOrder int
 ) 
go
--Store Constraints 
insert into DatabaseName.dbo.T_FK_Xref(ConstraintName,MasterTable,MasterColumn,ChildTable,ChildColumn,FKOrder)
  SELECT object_name(constid) as ConstraintName,object_name(rkeyid) MasterTable
      ,sc2.name MasterColumn
      ,object_name(fkeyid) ChildTable 
      ,sc1.name ChildColumn
      ,cast (sf.keyno as int) FKOrder
   FROM sysforeignkeys  sf
INNER JOIN syscolumns sc1 ON sf.fkeyid = sc1.id AND sf.fkey = sc1.colid
INNER JOIN syscolumns sc2 ON sf.rkeyid = sc2.id AND sf.rkey = sc2.colid
ORDER BY rkeyid,fkeyid,keyno

go

use databaseName --Database to removed constraints
go
---Ready to remove constraints

declare @ConstraintName varchar (max) -- Name of the Constraint
declare @ChildTable varchar (max) -- Name of Child Table
declare @MasterTable varchar (max)--Name of Parent Table
declare @ChildColumn varchar (max)--Column of Child Table FK
declare @MasterColumn varchar (max)-- Parent Column PK
declare @FKOrder smallint -- Fk order
declare @sqlcmd varchar (max) --Dynamic Sql String 


-- Create cursor to get constraint Information
declare drop_constraints cursor  
fast_forward 
for
SELECT object_name(constid) as ConstraintName,object_name(rkeyid) MasterTable
      ,sc2.name MasterColumn
      ,object_name(fkeyid) ChildTable 
      ,sc1.name ChildColumn
      ,cast (sf.keyno as int) FKOrder
   FROM sysforeignkeys  sf
INNER JOIN syscolumns sc1 ON sf.fkeyid = sc1.id AND sf.fkey = sc1.colid
INNER JOIN syscolumns sc2 ON sf.rkeyid = sc2.id AND sf.rkey = sc2.colid
ORDER BY rkeyid,fkeyid,keyno

open drop_constraints
fetch next from drop_constraints 
into
@ConstraintName
,@MasterTable
,@MasterColumn
,@ChildTable
,@ChildColumn
,@FKOrder
while @@Fetch_status = 0
begin

-- Create Dynamic Sql to drop constraint 

 select @sqlcmd = 'alter table '+@ChildTable+' drop constraint '+@ConstraintName--+' foreign key '+'('+@ChildColumn+')'+' references '+@MasterTable+' ('+@MasterColumn+')'+' on delete no action on update no action'
If EXISTs (select object_name(constid) from sysforeignkeys where object_name(constid) = @ConstraintName)
	exec (@sqlcmd)
fetch next from drop_constraints 
into
@ConstraintName
,@MasterTable
,@MasterColumn
,@ChildTable
,@ChildColumn
,@FKOrder
end
close drop_constraints
deallocate drop_constraints

go
--Removed CHECK Constraint-------------------------
EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL' --NOCHECK Constraints
print 'All Constraints Disable'
go

--truncate All tables  if trying to empty the database 
 --- Ensure the T_X_ref database is located on a different database

-------------  Truncate All Tables from Model ----------------
-----To limit tables a table with sub model tables must be created  and used joins-----
EXEC sp_MSForEachTable 'truncate TABLE ? '
print 'All tables truncated'
go

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