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 'DELETE FROM ?'
GO
EXEC sp_MSForEachTable 'ALTER TABLE ? 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

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 3

--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 4

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

Delete  FROM TABLE Where PRIMARY_KEY_ is Not NULL;

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

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