删除有两个字段相同的多条重复记录，只保存一条

要求 ：把T_FORM_RECEIPT表中[FORM_NAME_],[OPT_USER_]字段相同的重复记录，重复记录只留?[CREATE_DATE_]?最

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???????????? 大的那条记录

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表?： CREATE TABLE [dbo].[T_FORM_RECEIPT](
?????? ?[ID_] [varchar](32) COLLATE Chinese_PRC_CI_AS NOT NULL,
?????? ? [FORM_NAME_] [varchar](100) COLLATE Chinese_PRC_CI_AS NULL,
??????? [OPT_USER_] [varchar](32) COLLATE Chinese_PRC_CI_AS NULL,
?????? [CREATE_DATE_] [varchar](20) COLLATE Chinese_PRC_CI_AS NULL,
?????? [CONTENT_] [text] COLLATE Chinese_PRC_CI_AS NULL,
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

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解决办法：

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alert table T_FORM_RECEIPT add flag int? //添加标示列，为1的为有用的

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update T_FORM_RECEIPT set flag=1?? from (select max(create_Date_) as Date_,form_name_ as name_,opt_User_ as user_? from T_FORM_RECEIPT? group by form_name_,opt_User_?? having count(*) >1) as c? where create_Date_=c.Date_ and form_name_=c.name_? and? opt_User_=c.user_?? //多条重复中 保留[CREATE_DATE_]?最?大的那条记录

update T_FORM_RECEIPT set flag=1?? from (select min(id_) as id from T_FORM_RECEIPT? group by form_name_,opt_User_ having count(*) =1) as c? where id_ =c.id?? //两字段没有重复的，只有一条的，保留

delete from T_FORM_RECEIPT where flag is null? //删除那些flag不等于1的（在sqlserver 中null 不能由！=1识别出来，所以这么写）

（编辑：李大同）

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