sql 查询和删除冗余数据

最新推荐文章于 2025-06-04 10:41:50 发布

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最新推荐文章于 2025-06-04 10:41:50 发布

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分类专栏： SQL Server

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本文介绍了一种使用SQL查询和删除数据库表中重复记录的方法。首先通过构造特定的查询语句来找出重复的数据项，然后利用游标遍历并删除多余的重复记录，确保每个唯一标识组合仅保留一条记录。

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1. 查询重复数据

Select * From SF_Org_Relation_Department_User
Where (SF_Org_Relation_Department_User.OD_Id+'_'+SF_Org_Relation_Department_User.OU_Id) in (
Select OD_Id+'_'+OU_Id From SF_Org_Relation_Department_User group by OD_Id,OU_Id having COUNT(*)>1)

2. 删除重复数据，只保留一条

Declare @odid varchar(50)
Declare @ouid varchar(50)

DECLARE Table_Cursor CURSOR FOR
Select OD_Id,OU_Id From SF_Org_Relation_Department_User
  Where (SF_Org_Relation_Department_User.OD_Id+'_'+SF_Org_Relation_Department_User.OU_Id) in (
  Select OD_Id+'_'+OU_Id From SF_Org_Relation_Department_User group by OD_Id,OU_Id having COUNT(*)>1)
Open Table_Cursor
FETCH NEXT FROM Table_Cursor INTO @odid,@ouid
WHILE @@FETCH_STATUS = 0
BEGIN

Delete From SF_Org_Relation_Department_User Where OD_Id=@odid and OU_Id=@ouid
    and ORDU_Id not in (Select top 1 ORDU_Id From SF_Org_Relation_Department_User Where OD_Id=@odid and OU_Id=@ouid)

FETCH NEXT FROM Table_Cursor INTO @odid,@ouid
END
CLOSE Table_Cursor
DEALLOCATE Table_Cursor