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

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