How do you truncate all tables in a database using

Question

I have a test environment for a database that I want to reload with new data at the start of a testing cycle. I am not interested in rebuilding the entire database- just simply "re-setting" the data.

What is the best way to remove all the data from all the tables using TSQL? Are there system stored procedures, views, etc. that can be used? I do not want to manually create and maintain truncate table statements for each table- I would prefer it to be dynamic.

Answer 1

Truncating all of the tables will only work if you don't have any foreign key relationships between your tables, as SQL Server will not allow you to truncate a table with a foreign key.

An alternative to this is to determine the tables with foreign keys and delete from these first, you can then truncate the tables without foreign keys afterwards.

See http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=65341 and http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=72957 for further details.

Answer 2

The hardest part of truncating all tables is removing and re-ading the foreign key constraints.

The following query creates the drop & create statements for each constraint relating to each table name in @myTempTable. If you would like to generate these for all the tables, you may simple use information schema to gather these table names instead.

DECLARE @myTempTable TABLE (tableName varchar(200))
INSERT INTO @myTempTable(tableName) VALUES
('TABLE_ONE'),
('TABLE_TWO'),
('TABLE_THREE')


-- DROP FK Contraints
SELECT 'alter table '+quotename(schema_name(ob.schema_id))+
  '.'+quotename(object_name(ob.object_id))+ ' drop constraint ' + quotename(fk.name) 
  FROM sys.objects ob INNER JOIN sys.foreign_keys fk ON fk.parent_object_id = ob.object_id
  WHERE fk.referenced_object_id IN 
      (
         SELECT so.object_id 
         FROM sys.objects so JOIN sys.schemas sc
         ON so.schema_id = sc.schema_id
         WHERE so.name IN (SELECT * FROM @myTempTable)  AND sc.name=N'dbo'  AND type in (N'U'))


 -- CREATE FK Contraints
 SELECT 'ALTER TABLE [PIMSUser].[dbo].[' +cast(c.name as varchar(255)) + '] WITH NOCHECK ADD CONSTRAINT ['+ cast(f.name as varchar(255)) +'] FOREIGN KEY (['+ cast(fc.name as varchar(255)) +'])
      REFERENCES [PIMSUser].[dbo].['+ cast(p.name as varchar(255)) +'] (['+cast(rc.name as varchar(255))+'])'
FROM  sysobjects f
      INNER JOIN sys.sysobjects c ON f.parent_obj = c.id
      INNER JOIN sys.sysreferences r ON f.id = r.constid
      INNER JOIN sys.sysobjects p ON r.rkeyid = p.id
      INNER JOIN sys.syscolumns rc ON r.rkeyid = rc.id and r.rkey1 = rc.colid
      INNER JOIN sys.syscolumns fc ON r.fkeyid = fc.id and r.fkey1 = fc.colid
WHERE 
      f.type = 'F'
      AND
      cast(p.name as varchar(255)) IN (SELECT * FROM @myTempTable)

I then just copy out the statements to run - but with a bit of dev effort you could use a cursor to run them dynamically.

Answer 3

This is one way to do it... there are likely 10 others that are better/more efficient, but it sounds like this is done very infrequently, so here goes...

get a list of the tables from sysobjects, then loop over those with a cursor, calling sp_execsql('truncate table ' + @table_name) for each iteration.

Answer 4

Here's the king daddy of database wiping scripts. It will clear all tables and reseed them correctly:

SET QUOTED_IDENTIFIER ON;
EXEC sp_MSforeachtable 'SET QUOTED_IDENTIFIER ON; ALTER TABLE ? NOCHECK CONSTRAINT ALL'  
EXEC sp_MSforeachtable 'SET QUOTED_IDENTIFIER ON; ALTER TABLE ? DISABLE TRIGGER ALL'  
EXEC sp_MSforeachtable 'SET QUOTED_IDENTIFIER ON; DELETE FROM ?'  
EXEC sp_MSforeachtable 'SET QUOTED_IDENTIFIER ON; ALTER TABLE ? CHECK CONSTRAINT ALL'  
EXEC sp_MSforeachtable 'SET QUOTED_IDENTIFIER ON; ALTER TABLE ? ENABLE TRIGGER ALL' 
EXEC sp_MSforeachtable 'SET QUOTED_IDENTIFIER ON;

IF NOT EXISTS (
    SELECT
        *
    FROM
        SYS.IDENTITY_COLUMNS
        JOIN SYS.TABLES ON SYS.IDENTITY_COLUMNS.Object_ID = SYS.TABLES.Object_ID
    WHERE
        SYS.TABLES.Object_ID = OBJECT_ID(''?'') AND SYS.IDENTITY_COLUMNS.Last_Value IS NULL
)
AND OBJECTPROPERTY( OBJECT_ID(''?''), ''TableHasIdentity'' ) = 1

    DBCC CHECKIDENT (''?'', RESEED, 0) WITH NO_INFOMSGS'

Enjoy, but be careful!

Answer 5

For SQL 2005,

EXEC sp_MSForEachTable 'TRUNCATE TABLE ?'

Couple more links for 2000 and 2005/2008..

Answer 6

It is much easier (and possibly even faster) to script out your database, then just drop and create it from the script.