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

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 2

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 3

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 4

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 5

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'