Deleting Duplicate Rows_deleting dupicate-优快云博客

本文介绍了一种用于删除数据库表中指定列重复值的方法。通过对比同一列的不同行数据，如果发现重复，则删除对应的行。该方法适用于包含自动增长ID字段的表。

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--**************************************
--     
-- Name: Deleting Duplicate Rows
-- Description:The Purpose of this code 
--     is to delete the duplicate values occuri
--     ng in a table. This code is column-orien
--     ted. That means the code works for the d
--     uplicate values occuring in a specified 
--     column and deletes the values of the row
--     s corresponding to that column.
-- By: barkýn ünüulu
--
-- Inputs:I am going to specify the colu
--     mn name as COLUMNNAME and table name as 
--     TABLENAME. It should be noted that the d
--     evelopers that are willing to run this c
--     ode should put an "id" column in to thei
--     r tables, which increments automatically
--     .
--
-- Side Effects:As the row number increa
--     ses, the time elapsed for the code incre
--     ases...
--
--This code is copyrighted and has-- limited warranties.Please see http://
--     www.Planet-Source-Code.com/vb/scripts/Sh
--     owCode.asp?txtCodeId=936&lngWId=5--for details.--**************************************
--     

DECLARE @i int
DECLARE @j int
DECLARE @k int
SET @k=(select count(*) FROM TABLENAME)
SET @i=1
 WHILE @i<=@k


     BEGIN
    SET @j=@i+1
     WHILE @j<=@k


         BEGIN
         IF ((select COLUMNNAME FROM TABLENAME WHERE ID=@i)=
        (select COLUMNNAME FROM TABLENAME WHERE ID=@j))


            begin
             DELETE FROM TABLENAME
             WHERE ID=@j
        end

         SET @j=@j+1
    end

    SET @i=@i+1
 END