sql - 删除重复值 T-SQL 的 1 个实例

Question

我目前有一张名为 People 的表。在此表中，有数千行数据，其布局如下：

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

我得到回报：

Person_Id     | TotalCount
ABC123456     | 2

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

Answer 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

Answer 2

Try this

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

You can use either MIN or Max

Answer 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

Answer 4

使用带删除的 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，仅添加了 Top(1)...