数据去重高效方法

去重的方法有很多，比如用什么Distinct、 Group By Having、临时表等

有兴趣的朋友可以把各种方法对比一下得出直观的效率概况

WITH TEST AS
 (
    SELECT ROW_NUMBER() 
    OVER(PARTITION BY Column1,Column2,Column3 ORDER BY ID ) 
    AS NUM,* FROM TableName
 )
 DELETE FROM TEST
 WHERE NUM != 1

其中Column1,Column2,Column3为需要去重的列

TableName为需要去重的表