How to delete tables with specific names in SQL Server?

Question

Guru's please help me with this.

I have a master table called ABC , each month we create new table and suffix with month and year ABC_012010 , ABC_022010 .

I have to keep these tables for 7 years, and delete any table which are more than 7 years.

So the job would delete ABC_012010 in Feb 2017, ABC_022010 would be deleted in March 2017 and so on

The job runs every month to check and delete any table, which fits the criteria.

Answer 1

TRY THIS : You need dynamic query, loop and temporary tables to perform this operation and your table format must be in the same format as you have mentioned in your example. You can perform INSERT, UPDATE, DELETE, DROP, TRUNCATE in this way in multiple tables:

    --Selecting table name in date format with `LEFT` `RIGHT` function
SELECT name, 
    CAST(CONCAT(LEFT(RIGHT(name, 6), 2), '-01-', RIGHT(RIGHT(name, 6), 4)) AS DATE) AS tableDate, 
    CAST(GETDATE() AS DATE) AS currentDate
INTO #tmp_date 
FROM sys.objects 
WHERE TYPE = 'u' AND NAME LIKE 'ABC[_]%'

--Storing table names that are older than 7 years from current date
SELECT id = IDENTITY(INT, 1, 1), 
    NAME 
INTO #object_name FROM #tmp_date 
WHERE (DATEDIFF(MM,tableDate, currentDate)-1) > = 84 

DECLARE @i INT = 1, @j INT, @sql VARCHAR(500), @object_name VARCHAR(100)

SELECT @j = MAX(id) FROM #object_name

WHILE @i < = @j 
BEGIN
    SELECT @object_name = NAME FROM #object_name WHERE id = @i
    SET @sql = 'DELETE FROM ' + @object_name --can use `DROP` to drop the table
    EXEC (@sql)

    SET @i = @i+1

END

Answer 2

try the following:

IF OBJECT_ID('TEMPDB.DBO.#TEMP_DEL', 'U') IS NOT NULL
    DROP TABLE #TEMP_DEL
DECLARE @CYMO VARCHAR(8) = (SELECT '01' + RIGHT(REPLACE(CONVERT(CHAR(10), DATEADD(YY, -7, GETDATE()), 103), '/', ''), 6))
SELECT [NAME] TABLE_NAME INTO #TEMP_DEL FROM DBNAME.SYS.TABLES
WHERE [NAME] LIKE 'ABC%' AND '01'+RIGHT(NAME,6) < @CYMO
WHILE ((SELECT COUNT(1) FROM #TEMP_DEL) > 0)
BEGIN
    DECLARE @TAB VARCHAR(100) = (SELECT TOP 1 TABLE_NAME FROM #TEMP_DEL)
    DECLARE @CMD NVARCHAR(200) = 'DROP TABLE '+@TAB
    EXEC SP_EXECUTESQL @CMD
    DELETE #TEMP_DEL WHERE TABLE_NAME = @TAB
END

Replace DBNAME with your database name.

HTH!

Thanks.

Answer 3

You could use dynamic query, while and if conditionals to construct a stored procedure or scheduled job (as you like) to solve this issue. Try this.

CREATE PROCEDURE dbo.delete_abc @Date date, @years_diff int
AS 
    --- Declare variables to use
    DECLARE @sqlCommand varchar(30)
    DECLARE @table varchar(20)
    DECLARE @month int
    DECLARE @year int

    --- Temporary table with 'ABC_'s table names
    SELECT TABLE_NAME
    INTO #Temp
    FROM INFORMATION_SCHEMA.TABLES 
    WHERE TABLE_NAME LIKE 'ABC_%'
    AND TABLE_TYPE='BASE TABLE' -- If you want only tables

    ---- While there are tables to compare
    WHILE EXISTS(SELECT * FROM #Temp)
    BEGIN
        --- Extract Month and Year of the first row in 'ABC_'s table
        SET @month = (SELECT TOP 1 SUBSTRING(TABLE_NAME,5,2) FROM #Temp)
        SET @year = (SELECT TOP 1 SUBSTRING(TABLE_NAME,7,4) FROM #Temp)

        --- Compare if date difference of the table is more than @years_diff years from @Date
        IF DATEDIFF(YEAR, CAST(CAST(@year AS VARCHAR) + '-' + CAST(@month AS VARCHAR) + '-01' AS DATE), DATEADD(MONTH, DATEDIFF(MONTH, 0, @Date), 0)) > @years_diff 
            BEGIN
            --- Construct and execute delete query
            SET @table = (SELECT TOP 1 TABLE_NAME FROM #Temp)
            SET @sqlCommand = 'DROP TABLE ' + @table  --- or 'DELETE FROM ' if you only want to delete all rows from table
            EXEC(@sqlCommand)
            END

     --- Delete first row of 'ABC_'s tables in temporary
     DELETE TOP (1) FROM #Temp;

     END

     --- Drop temporary table
     DROP TABLE #Temp
GO;

Once it's created, you can use this stored procedure like this or with the parameters you like:

DECLARE @Now date
SET @Now = GETDATE()
EXEC dbo.delete_abc @years_diff = 7, @Date = @Now

Answer 4

进行删除查询是否足够容易？

Delete From [Your_Table] Where [Date_Column] = 'ABC_012010'