How to delete all rows from all tables in a SQL Server database?

Question

How to delete all rows from all tables in a SQL Server database?

Answer 1

Note that TRUNCATE won't work if you have any referential integrity set.

In that case, this will work:

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

Edit: To be clear, the ? in the statements is a ?. It's replaced with the table name by the sp_MSForEachTable procedure.

Answer 2

In my recent project my task was to clean an entire database by using sql statement and each table having many constraints like Primary Key and Foreign Key. There are more than 1000 tables in database so its not possible to write a delete query on each and ever table.

By using a stored procedure named sp_MSForEachTable which allows us to easily process some code against each and every table in a single database. It means that it is used to process a single T-SQL command or a different T-SQL commands against every table in the database.

So follow the below steps to truncate all tables in a SQL Server Database:

Step 1- Disable all constraints on the database by using below sql query :

EXEC sys.sp_msforeachtable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL'

Step 2- Execute a Delete or truncate operation on each table of the database by using below sql command :

EXEC sys.sp_msforeachtable 'DELETE FROM ?'

Step 3- Enable all constraints on the database by using below sql statement:

EXEC sys.sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL'

Answer 3

I had to delete all the rows and did it with the next script:

DECLARE @Nombre NVARCHAR(MAX);
DECLARE curso CURSOR FAST_FORWARD 
FOR 
Select Object_name(object_id) AS Nombre from sys.objects where type = 'U'

OPEN curso
FETCH NEXT FROM curso INTO @Nombre

WHILE (@@FETCH_STATUS <> -1)
BEGIN
IF (@@FETCH_STATUS <> -2)
BEGIN
DECLARE @statement NVARCHAR(200);
SET @statement = 'DELETE FROM ' + @Nombre;
print @statement
execute sp_executesql @statement;
END
FETCH NEXT FROM curso INTO @Nombre
END
CLOSE curso
DEALLOCATE curso

Hope this helps!

Answer 4

In my case, I needed to set QUOTED_IDENTIFIER on. This led to a slight modification of Mark Rendle's answer above:

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

Answer 5

Here is a solution that:

1. Drops constraints (thanks to this post)
2. Iterates through INFORMATION_SCHEMA.TABLES for a particular database
3. SELECTS tables based on some search criteria
4. Deletes all the data from those tables
5. Re-adds constraints
6. Allows for ignoring of certain tables such as sysdiagrams and __RefactorLog

I initially tried EXECUTE sp_MSforeachtable 'TRUNCATE TABLE ?', but that deleted my diagrams.

USE <DB name>;
GO

-- Disable all constraints in the database
EXEC sp_MSforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT all"

declare @catalog nvarchar(250);
declare @schema nvarchar(250);
declare @tbl nvarchar(250);
DECLARE i CURSOR LOCAL FAST_FORWARD FOR select
                                        TABLE_CATALOG,
                                        TABLE_SCHEMA,
                                        TABLE_NAME
                                        from INFORMATION_SCHEMA.TABLES
                                        where
                                        TABLE_TYPE = 'BASE TABLE'
                                        AND TABLE_NAME != 'sysdiagrams'
                                        AND TABLE_NAME != '__RefactorLog'

OPEN i;
FETCH NEXT FROM i INTO @catalog, @schema, @tbl;
WHILE @@FETCH_STATUS = 0
    BEGIN
        DECLARE @sql NVARCHAR(MAX) = N'DELETE FROM [' + @catalog + '].[' + @schema + '].[' + @tbl + '];'
        /* Make sure these are the commands you want to execute before executing */
        PRINT 'Executing statement: ' + @sql
        -- EXECUTE sp_executesql @sql
        FETCH NEXT FROM i INTO @catalog, @schema, @tbl;
    END
CLOSE i;
DEALLOCATE i;

-- Re-enable all constraints again
EXEC sp_MSforeachtable "ALTER TABLE ? WITH CHECK CHECK CONSTRAINT all"

Answer 6

Set nocount on

Exec sp_MSforeachtable 'Alter Table ? NoCheck Constraint All'

Exec sp_MSforeachtable
'
If ObjectProperty(Object_ID(''?''), ''TableHasForeignRef'')=1
Begin
-- Just to know what all table used delete syntax.
Print ''Delete from '' + ''?''
Delete From ?
End
Else
Begin
-- Just to know what all table used Truncate syntax.
Print ''Truncate Table '' + ''?''
Truncate Table ?
End
'

Exec sp_MSforeachtable 'Alter Table ? Check Constraint All'

Answer 7

If you just have constraints just paste this lines in the query and run it

EXEC sys.sp_msforeachtable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL' 
EXEC sys.sp_msforeachtable 'DELETE FROM ?'
EXEC sys.sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL' 

Answer 8

You could delete all the rows from all tables using an approach like Rubens suggested, or you could just drop and recreate all the tables. Always a good idea to have the full db creation scripts anyway so that may be the easiest/quickest method.

Answer 9

This answer builds on Zach Smith's answer by resetting the identity column as well:

1. Disabling all constraints
2. Iterating through all tables except those you choose to exclude
3. Deletes all rows from the table
4. Resets the identity column if one exists
5. Re-enables all constraints

Here is the query:

-- Disable all constraints in the database
EXEC sp_msforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT all"

declare @catalog nvarchar(250);
declare @schema nvarchar(250);
declare @tbl nvarchar(250);
DECLARE i CURSOR LOCAL FAST_FORWARD FOR select
                                        TABLE_CATALOG,
                                        TABLE_SCHEMA,
                                        TABLE_NAME
                                        from INFORMATION_SCHEMA.TABLES
                                        where
                                        TABLE_TYPE = 'BASE TABLE'
                                        AND TABLE_NAME != 'sysdiagrams'
                                        AND TABLE_NAME != '__RefactorLog'
                                        -- Optional
                                        -- AND (TABLE_SCHEMA = 'dbo')

OPEN i;
FETCH NEXT FROM i INTO @catalog, @schema, @tbl;
WHILE @@FETCH_STATUS = 0
    BEGIN
        DECLARE @sql NVARCHAR(MAX) = N'DELETE FROM [' + @catalog + '].[' + @schema + '].[' + @tbl + '];'
        /* Make sure these are the commands you want to execute before executing */
        PRINT 'Executing statement: ' + @sql
        --EXECUTE sp_executesql @sql

        -- Reset identity counter if one exists
        IF ((SELECT OBJECTPROPERTY( OBJECT_ID(@catalog + '.' + @schema + '.' + @tbl), 'TableHasIdentity')) = 1)
        BEGIN
            SET @sql = N'DBCC CHECKIDENT ([' + @catalog + '.' + @schema + '.' + @tbl + '], RESEED, 0)'
            PRINT 'Executing statement: ' + @sql
            --EXECUTE sp_executesql @sql
        END     

        FETCH NEXT FROM i INTO @catalog, @schema, @tbl;
    END
CLOSE i;
DEALLOCATE i;

-- Re-enable all constraints again
EXEC sp_msforeachtable "ALTER TABLE ? WITH CHECK CHECK CONSTRAINT all"

Answer 10

For some requirements we might have to skip certain tables. I wrote the below script to add some extra conditions to filter the list of tables. The below script will also display the pre delete count and post delete count.

        IF OBJECT_ID('TEMPDB..#TEMPRECORDCOUNT') IS NOT NULL 
        DROP TABLE #TEMPRECORDCOUNT 

        CREATE TABLE #TEMPRECORDCOUNT 
            (    TABLENAME NVARCHAR(128)
                ,PREDELETECOUNT BIGINT
                ,POSTDELETECOUNT BIGINT
            ) 

        INSERT INTO #TEMPRECORDCOUNT (TABLENAME, PREDELETECOUNT, POSTDELETECOUNT)

        SELECT   O.name TableName
                ,DDPS.ROW_COUNT PREDELETECOUNT
                ,NULL  FROM sys.objects O 

        INNER JOIN (

                    SELECT OBJECT_ID, SUM(row_count) ROW_COUNT 
                    FROM SYS.DM_DB_PARTITION_STATS
                    GROUP BY OBJECT_ID
                   ) DDPS ON DDPS.OBJECT_ID = O.OBJECT_ID
        WHERE O.type = 'U' AND O.name NOT LIKE 'OC%' AND O.schema_id = 1

        DECLARE @TableName NVARCHAR(MAX);
        DECLARE TableDeleteCursor CURSOR FAST_FORWARD 
        FOR 
        SELECT TableName from #TEMPRECORDCOUNT

        OPEN TableDeleteCursor
        FETCH NEXT FROM TableDeleteCursor INTO @TableName

        WHILE (@@FETCH_STATUS <> -1)
        BEGIN
        IF (@@FETCH_STATUS <> -2)
        BEGIN
        DECLARE @STATEMENT NVARCHAR(MAX);
        SET @STATEMENT = ' DISABLE TRIGGER ALL ON ' + @TableName + 
                         '; ALTER TABLE ' + @TableName + ' NOCHECK CONSTRAINT ALL' +
                         '; DELETE FROM ' + @TableName +
                         '; ALTER TABLE ' + @TableName + ' CHECK CONSTRAINT ALL' +
                         '; ENABLE TRIGGER ALL ON ' + @TableName;
        PRINT @STATEMENT
        EXECUTE SP_EXECUTESQL @STATEMENT;
        END
        FETCH NEXT FROM TableDeleteCursor INTO @TableName
        END
        CLOSE TableDeleteCursor
        DEALLOCATE TableDeleteCursor

        UPDATE T 
         SET T.POSTDELETECOUNT = I.ROW_COUNT 
         FROM #TEMPRECORDCOUNT T 
         INNER JOIN (
                        SELECT O.name TableName, DDPS.ROW_COUNT ROW_COUNT  
                        FROM sys.objects O 
                        INNER JOIN (

                                SELECT OBJECT_ID, SUM(row_count) ROW_COUNT 
                                FROM SYS.DM_DB_PARTITION_STATS
                                GROUP BY OBJECT_ID
                               ) DDPS ON DDPS.OBJECT_ID = O.OBJECT_ID
                        WHERE O.type = 'U' AND O.name NOT LIKE 'OC%' AND O.schema_id = 1

                    ) I ON I.TableName COLLATE DATABASE_DEFAULT = T.TABLENAME 

        SELECT * FROM #TEMPRECORDCOUNT 
        ORDER BY TABLENAME ASC

Answer 11

--Load tables to delete from
SELECT 
DISTINCT
' Delete top 1000000 from <DBName>.<schema>.' + c.TABLE_NAME + ' WHERE <Filter Clause Here>' AS query,c.TABLE_NAME AS TableName, IsDeleted=0, '<InsertSomeDescriptorHere>' AS [Source]--,t.TABLE_TYPE, c.*
            INTO dbo.AllTablesToDeleteFrom
            FROM INFORMATION_SCHEMA.TABLES AS t
            INNER JOIN information_schema.columns c ON c.TABLE_NAME = t.TABLE_NAME 
    WHERE c.COLUMN_NAME = '<column name>'
           AND c.TABLE_SCHEMA = 'dbo'
           AND c.TABLE_CATALOG = '<DB Name here>'
           AND t.TABLE_TYPE='Base table'
           --AND t.TABLE_NAME LIKE '<put filter here>'

            DECLARE @TableSelect NVARCHAR(1000)= '';
            DECLARE @Table NVARCHAR(1000)= '';
            DECLARE @IsDeleted INT= 0;
            DECLARE @NumRows INT = 1000000;
            DECLARE @Source NVARCHAR(50)='';


            WHILE ( @IsDeleted = 0 )
                BEGIN
                --This grabs one table at a time to be deleted from. @TableSelect has the sql to execute. it is important to order by IsDeleted ASC
                --because it will pull tables to delete from by those that have a 0=IsDeleted first. Once the loop grabs a table with IsDeleted=1 then this will pop out of loop

                    SELECT TOP 1
                            @TableSelect = query,
                            @IsDeleted = IsDeleted,
                            @Table = TableName,
                            @Source=[a].[Source]
                    FROM    dbo.AllTablesToDeleteFrom a
                    WHERE a.[Source]='SomeDescriptorHere'--use only if needed
                    ORDER BY a.IsDeleted ASC;--this is required because only those records returned with IsDeleted=0 will run through loop

                    --SELECT  @Table; can add this in to  monitor what table is being deleted from

                    WHILE ( @NumRows = 1000000 )--only delete a million rows at a time?

                    BEGIN 
                    EXEC sp_executesql @TableSelect;
                    SET @NumRows = @@ROWCOUNT;
                    --IF @NumRows = 1000000 --can do something here if needed
                    --One wants this loop to continue as long as a million rows is deleted. Once < 1 million rows is deleted it pops out of loop
                    --and grabs next table to delete
                    --    BEGIN
                    --SELECT  @NumRows;--can add this in to see current number of deleted records for table
                            INSERT  INTO dbo.DeleteFromAllTables
                                    ( tableName,
                                      query,
                                      cnt,
                                      [Source]
                                    )
                            SELECT  @Table,
                                    @TableSelect,
                                    @NumRows,
                                    @Source;
                     --   END; 
                END; 



SET @NumRows = 1000000;

UPDATE  a
SET     a.IsDeleted = 1
FROM    dbo.AllTablesToDeleteFrom a
WHERE   a.TableName = @Table;
--flag this as deleted so you can move on to the next table to delete from

END; 

Answer 12

if you want to delete the whole table, you must follow the next SQL instruction

Delete  FROM TABLE Where PRIMARY_KEY_ is Not NULL;