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BI SQL # 146 : SQL Server DBA Scripts : Delete duplicates from any table

July 31, 2013 7:00 am

Hi Folks,

In this article we are going to cover How to Delete duplicates from any table.

In this post we are going to discuss following points:

• Problem Statement of SQL Script:
• Description of SQL Script:
• Input Parameter of SQL Script
• SQL Script Code
• SQL Script Output Screenshot
• User Level to execute

Problem Statement of SQL Script:

Delete duplicates from any table.

Description of SQL Script:

Stored procedure in TSQL based on dynamic SQL to delete any duplicate rows in any table.You need to pass table name to @tableName.If you pass 1 to @check the duplicates will be deleted, but if you pass 0 to @check, the duplicates will be displayed.

Input Parameter of SQL Script

@Tablename sysname, @Check int

SQL Script Code

IF EXISTS (
        SELECT 1
        FROM SYSOBJECTS
        WHERE NAME = 'deleteDuplicates'
            AND xtype = 'P'
        )
    DROP PROCEDURE deleteDuplicates
GO

CREATE PROCEDURE dbo.deleteDuplicates (
    @tableName SYSNAME
    ,@check INT = 0 
    --- 0 just to see what are duplicates, 1 delete the duplicates. 
    )
AS
BEGIN
    DECLARE @columnsDelimited NVARCHAR(max)
        ,@dySql NVARCHAR(max)
        ,@tran INT
        ,@tempTable SYSNAME

    SET @tran = 0
    SET @columnsDelimited = ''
    SET @tempTable = 'delteDuplicates' + CAST(@@SPID AS VARCHAR)

    BEGIN TRY
        IF NOT EXISTS (
                SELECT 1
                FROM sys.tables
                WHERE NAME = @tableName
                )
        BEGIN
            PRINT @tableName + 
                ' not exists in the current database'

            RETURN - 1
        END

        SELECT @columnsDelimited = @columnsDelimited + CASE LEN(
                    @columnsDelimited)
                WHEN 0
                    THEN ''
                ELSE ','
                END + QUOTENAME(c.NAME)
        FROM sys.columns C
        JOIN sys.tables T ON C.object_id = T.object_id
            AND c.is_identity = 0
            AND T.NAME = @tableName

        IF OBJECT_ID(@tempTable) IS NOT NULL
        BEGIN
            SET @dySql = 'DROP TABLE ' + @tempTable

            EXEC (@dySql)
        END

        SET @dySql = 'SELECT ROW_NUMBER() OVER(PARTITION BY ' + 
            @columnsDelimited + ' ORDER BY ' + @columnsDelimited 
            + ' ) as row_number_delete, * into ' + @tempTable + 
            ' FROM ' + @tableName

        EXEC sp_executeSQl @dySql

        SELECT @dySql

        IF (@check = 0)
        BEGIN
            SET @dySql = 'SELECT * FROM ' + @tempTable + 
                ' WHERE row_number_delete > 1 '

            EXEC (@dySql)
        END

        IF (@check = 1)
        BEGIN
            SET @dySql = 'DELETE ' + @tempTable + 
                ' WHERE row_number_delete > 1'

            EXEC (@dySql)

            BEGIN TRAN

            SET @tran = 1
            SET @dySql = 'TRUNCATE TABLE ' + @tableName

            EXEC (@dySql)

            SET @dySql = 'INSERT INTO ' + @tableName + ' (' + 
                @columnsDelimited + ') ' + 'SELECT ' + 
                @columnsDelimited + ' FROM ' + @tempTable

            EXEC (@dySql)

            COMMIT TRAN
        END
    END TRY

    BEGIN CATCH
        IF (@tran = 1)
            ROLLBACK;

        SELECT 'errored_line ' + CAST(ERROR_LINE() AS VARCHAR) + 
            ' error_msg ' + ERROR_MESSAGE() + ' error_number ' + 
            ERROR_NUMBER()
    END CATCH;
END
GO

SQL Script Output Screenshot



User Level to execute

400

Hope you will like How to Delete duplicates from any table.

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Posted by Vishal Pawar

Categories: Link, Microsoft SQL Server, MSBI, Optimization, Query, Script, SQL Mentalist, SQL PraRup, SQL Query, SQL Server, Technology,, TSQL, Vishal Pawar

Tags: DBA, Fast SQL, Microsoft SQL Server, SQL Help, SQL Mentalist, SQL Script, SQL Server, SQL Server 2008 R2, SQL Server 2012, SQL tips, SQL Tricks, TSQL, Vishal Pawar

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