[sql] Delete all data in SQL Server database

How I can delete all records from all tables of my database? Can I do it with one SQL command or I need for one SQL command per one table?

I'm aware this is late, but I agree with AlexKuznetsov's suggestion to script the database, rather than going through the hassle of purging the data from the tables. If the TRUNCATE solution will not work, and you happen to have a large amount of data, issuing (logged) DELETE statements might take a long time, and you'll be left with identifiers that have not been reseeded (i.e. an INSERT statement into a table with an IDENTITY column would get you an ID of 50000 instead of an ID of 1).

To script a whole database, in SSMS, right-click the database, then select TASKS -> Generate scripts:

Click Next to skip the Wizard opening screen, and then select which objects you want to script:

In the Set scripting options screen, you can pick settings for the scripting, like whether to generate 1 script for all the objects, or separate scripts for the individual objects, and whether to save the file in Unicode or ANSI:

The wizard will show a summary, which you can use to verify everything is as desired, and close by clicking on 'Finish'.

Yes, it is possible to delete with a single line of code

SELECT 'TRUNCATE TABLE ' + d.NAME + ';' 
FROM   sys.tables d 
WHERE  type = 'U' 

Below a script that I used to remove all data from an SQL Server database

------------------------------------------------------------
/* Use database */ 
-------------------------------------------------------------

use somedatabase;

GO

------------------------------------------------------------------
/* Script to delete an repopulate the base [init database] */
------------------------------------------------------------------

-------------------------------------------------------------
/* Procedure delete all constraints */ 
-------------------------------------------------------------

IF EXISTS (SELECT name  
           FROM  sysobjects 
           WHERE name = 'sp_DeleteAllConstraints' AND type = 'P')
    DROP PROCEDURE dbo.sp_DeleteAllConstraints
GO

CREATE PROCEDURE sp_DeleteAllConstraints
AS
    EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL'
    EXEC sp_MSForEachTable 'ALTER TABLE ? DISABLE TRIGGER ALL'
GO

-----------------------------------------------------
/* Procedure delete all data from the database */ 
-----------------------------------------------------

IF EXISTS (SELECT name  
           FROM  sysobjects 
           WHERE name = 'sp_DeleteAllData' AND type = 'P')
    DROP PROCEDURE dbo.sp_DeleteAllData
GO

CREATE PROCEDURE sp_DeleteAllData
AS
    EXEC sp_MSForEachTable 'DELETE FROM ?'
GO

-----------------------------------------------
/* Procedure enable all constraints */ 
-----------------------------------------------

IF EXISTS (SELECT name  
           FROM  sysobjects 
           WHERE name = 'sp_EnableAllConstraints' AND type = 'P')
    DROP PROCEDURE dbo.sp_EnableAllConstraints
GO
-- ....
-- ....
-- ....

1. First you'll have to disable all the triggers :

   sp_msforeachtable 'ALTER TABLE ? DISABLE TRIGGER all';
   

2. Run this script : (Taken from this post Thank you @SQLMenace)

   SET NOCOUNT ON
   GO
   
   SELECT 'USE [' + db_name() +']';
   ;WITH a AS 
   (
        SELECT 0 AS lvl, 
               t.object_id AS tblID 
        FROM sys.TABLES t
        WHERE t.is_ms_shipped = 0
          AND t.object_id NOT IN (SELECT f.referenced_object_id 
                                  FROM sys.foreign_keys f)
   
        UNION ALL
   
        SELECT a.lvl + 1 AS lvl, 
               f.referenced_object_id AS tblId
        FROM a
        INNER JOIN sys.foreign_keys f ON a.tblId = f.parent_object_id 
                                      AND a.tblID <> f.referenced_object_id
   )
   SELECT 
       'Delete from ['+ object_schema_name(tblID) + '].[' + object_name(tblId) + ']' 
   FROM a
   GROUP BY tblId 
   ORDER BY MAX(lvl),1
   

This script will produce DELETE statements in proper order. starting from referenced tables then referencing ones

3. Copy the DELETE FROM statements and run them once

4. enable triggers

   sp_msforeachtable 'ALTER TABLE ? ENABLE TRIGGER all'
   

5. Commit the changes :

   begin transaction
   commit;
   

As an alternative answer, if you Visual Studio SSDT or possibly Red Gate Sql Compare, you could simply run a schema comparison, script it out, drop the old database (possibly make a backup first in case there would be a reason that you will need that data), and then create a new database with the script created by the comparison tool. While on a very small database this may be more work, on a very large database it will be much quicker to simply drop the database then to deal with the different triggers and constraints that may be on the database.

Usually I will just use the undocumented proc sp_MSForEachTable

-- disable referential integrity
EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL' 
GO 

EXEC sp_MSForEachTable 'TRUNCATE TABLE ?' 
GO 

-- enable referential integrity again 
EXEC sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL' 
GO

See also: Delete all data in database (when you have FKs)

/* Drop all non-system stored procs */
DECLARE @name VARCHAR(128)
DECLARE @SQL VARCHAR(254)

SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'P' AND category = 0 ORDER BY [name])

WHILE @name is not null
BEGIN
    SELECT @SQL = 'DROP PROCEDURE [dbo].[' + RTRIM(@name) +']'
    EXEC (@SQL)
    PRINT 'Dropped Procedure: ' + @name
    SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'P' AND category = 0 AND [name] > @name ORDER BY [name])
END
GO

/* Drop all views */
DECLARE @name VARCHAR(128)
DECLARE @SQL VARCHAR(254)

SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'V' AND category = 0 ORDER BY [name])

WHILE @name IS NOT NULL
BEGIN
    SELECT @SQL = 'DROP VIEW [dbo].[' + RTRIM(@name) +']'
    EXEC (@SQL)
    PRINT 'Dropped View: ' + @name
    SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'V' AND category = 0 AND [name] > @name ORDER BY [name])
END
GO

/* Drop all functions */
DECLARE @name VARCHAR(128)
DECLARE @SQL VARCHAR(254)

SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] IN (N'FN', N'IF', N'TF', N'FS', N'FT') AND category = 0 ORDER BY [name])

WHILE @name IS NOT NULL
BEGIN
    SELECT @SQL = 'DROP FUNCTION [dbo].[' + RTRIM(@name) +']'
    EXEC (@SQL)
    PRINT 'Dropped Function: ' + @name
    SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] IN (N'FN', N'IF', N'TF', N'FS', N'FT') AND category = 0 AND [name] > @name ORDER BY [name])
END
GO

/* Drop all Foreign Key constraints */
DECLARE @name VARCHAR(128)
DECLARE @constraint VARCHAR(254)
DECLARE @SQL VARCHAR(254)

SELECT @name = (SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'FOREIGN KEY' ORDER BY TABLE_NAME)

WHILE @name is not null
BEGIN
    SELECT @constraint = (SELECT TOP 1 CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'FOREIGN KEY' AND TABLE_NAME = @name ORDER BY CONSTRAINT_NAME)
    WHILE @constraint IS NOT NULL
    BEGIN
        SELECT @SQL = 'ALTER TABLE [dbo].[' + RTRIM(@name) +'] DROP CONSTRAINT [' + RTRIM(@constraint) +']'
        EXEC (@SQL)
        PRINT 'Dropped FK Constraint: ' + @constraint + ' on ' + @name
        SELECT @constraint = (SELECT TOP 1 CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'FOREIGN KEY' AND CONSTRAINT_NAME <> @constraint AND TABLE_NAME = @name ORDER BY CONSTRAINT_NAME)
    END
SELECT @name = (SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'FOREIGN KEY' ORDER BY TABLE_NAME)
END
GO

/* Drop all Primary Key constraints */
DECLARE @name VARCHAR(128)
DECLARE @constraint VARCHAR(254)
DECLARE @SQL VARCHAR(254)

SELECT @name = (SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'PRIMARY KEY' ORDER BY TABLE_NAME)

WHILE @name IS NOT NULL
BEGIN
    SELECT @constraint = (SELECT TOP 1 CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'PRIMARY KEY' AND TABLE_NAME = @name ORDER BY CONSTRAINT_NAME)
    WHILE @constraint is not null
    BEGIN
        SELECT @SQL = 'ALTER TABLE [dbo].[' + RTRIM(@name) +'] DROP CONSTRAINT [' + RTRIM(@constraint)+']'
        EXEC (@SQL)
        PRINT 'Dropped PK Constraint: ' + @constraint + ' on ' + @name
        SELECT @constraint = (SELECT TOP 1 CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'PRIMARY KEY' AND CONSTRAINT_NAME <> @constraint AND TABLE_NAME = @name ORDER BY CONSTRAINT_NAME)
    END
SELECT @name = (SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'PRIMARY KEY' ORDER BY TABLE_NAME)
END
GO

/* Drop all tables */
DECLARE @name VARCHAR(128)
DECLARE @SQL VARCHAR(254)

SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'U' AND category = 0 ORDER BY [name])

WHILE @name IS NOT NULL
BEGIN
    SELECT @SQL = 'DROP TABLE [dbo].[' + RTRIM(@name) +']'
    EXEC (@SQL)
    PRINT 'Dropped Table: ' + @name
    SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'U' AND category = 0 AND [name] > @name ORDER BY [name])
END
GO

EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL'

EXEC sp_MSForEachTable 'ALTER TABLE ? DISABLE TRIGGER ALL'

EXEC sp_MSForEachTable 'DELETE FROM ?'

EXEC sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL'

EXEC sp_MSForEachTable 'ALTER TABLE ? ENABLE TRIGGER ALL'

EXEC sp_MSFOREACHTABLE 'SELECT * FROM ?'

GO

It is usually much faster to script out all the objects in the database, and create an empty one, that to delete from or truncate tables.