删除重复值 T-SQL 的 1 个实例 [重复]答案

【问题标题】：Remove 1 instance of duplicate values T-SQL [duplicate]删除重复值 T-SQL 的 1 个实例 [重复]
【发布时间】：2013-07-02 08:48:51
【问题描述】：

我目前有一个名为 People 的表。此表中有数千行数据，布局如下：

gkey |    Name |  Date       | Person_Id
1    |    Fred |  12/05/2012 | ABC123456
2    |    John |  12/05/2012 | DEF123456
3    |    Dave |  12/05/2012 | GHI123456
4    |    Fred |  12/05/2012 | JKL123456
5    |    Leno |  12/05/2012 | ABC123456

如果我执行以下操作：

SELECT [PERSON_ID], COUNT(*) TotalCount
FROM [Database].[dbo].[People]
GROUP BY [PERSON_ID]
HAVING COUNT(*) > 1
ORDER BY COUNT(*) DESC

我得到一个回报：

Person_Id     | TotalCount
ABC123456     | 2

现在我只想删除一行重复值，所以当我执行上述查询时，我不会返回任何结果。这可能吗？

【问题讨论】：

我看不到重复值，您要删除 Fred 或 Leno（具有相同 Person_ID）吗？是否有做出此类决定的规则？

标签： sql tsql sql-server-2008-r2

【解决方案1】：

WITH a as
(
SELECT row_number() over (partition by [PERSON_ID] order by name) rn
FROM [Database].[dbo].[People]
)
DELETE FROM a
WHERE rn = 2

【讨论】：

谢谢。欣赏它

【解决方案2】：

试试这个

DELETE FROM [People]
WHERE gkey IN
(
   SELECT MIN(gkey)
   FROM [People]
    GROUP BY [PERSON_ID]
   HAVING COUNT(*) > 1
)

您可以使用MIN 或Max

【讨论】：

【解决方案3】：

DELETE FROM PEOPLE WHERE gkey=
(SELECT MAX(TABLE1.gkey) FROM (SELECT P.gkey, A.PERSON_ID,A.TotalCount FROM People P,(SELECT [PERSON_ID], COUNT(*) TotalCount
FROM [Database].[dbo].[People]
GROUP BY [PERSON_ID]
HAVING COUNT(*) > 1
ORDER BY COUNT(*) DESC) A WHERE P.gkey=A.gkey) TABLE1 ) TABLE2

【讨论】：

【解决方案4】：

在删除中使用 Top 关键字；

DELETE TOP(1) FROM [People]
WHERE Person_Id IN
(
   SELECT MIN([PERSON_ID])
   FROM [People]
   GROUP BY [PERSON_ID]
   HAVING COUNT(*) > 1

)

该查询与 Vassy 发布的查询相同，只是添加了 Top(1)...

【讨论】：