如何从表中删除除按日期列的最小值和最大值之外的所有行

Question

我有一张表Visitors，其中包含以下列

ID、Visitors、RegDate (date & time)

行：有 4、6、8、20、11、31、43 位访问者具有相同的日期（7 月 18 日），但时间不同。

另一行：有 1、5、10、4、13、15、18、11、23 位访客，日期相同（7 月 19 日）但时间不同。

类似的东西

Id  RegDate
4   2015-07-18 11:11:00.000
6   2015-07-18 11:11:01.000
8   2015-07-18 11:11:02.000
20  2015-07-18 11:11:03.000
11  2015-07-18 11:11:04.000
31  2015-07-18 11:11:05.000
43  2015-07-18 11:11:06.000
1   2015-07-19 11:11:00.000
10  2015-07-19 11:11:01.000
4   2015-07-19 11:11:02.000
13  2015-07-19 11:11:03.000
15  2015-07-19 11:11:04.000
18  2015-07-19 11:11:05.000
11  2015-07-19 11:11:06.000
23  2015-07-19 11:11:07.000

这是我的查询，显示包括日期在内的最小值和最大值。

SELECT MIN(Visitors), MAX(Visitors), cast(RegDate as date) AS DATE
FROM Visitor GROUP BY cast(RegDate as date)
ORDER BY DATE

我想从“访问者”列中删除除 RegDate 的最小值和最大值之外的所有行。

Answer 1

您可以使用ROW_NUMBER查找Visitor最早和最新的RegDate：

WITH Cte AS(
    SELECT *,
        RN_ASC = ROW_NUMBER() OVER(PARTITION BY CAST(RegDate AS DATE) ORDER BY RegDate ASC),
        RN_DESC = ROW_NUMBER() OVER(PARTITION BY CAST(RegDate AS DATE) ORDER BY RegDate DESC)
    FROM Visitor
)
DELETE FROM Cte WHERE RN_ASC > 1 AND RN_DESC > 1

SQLFiddle

Answer 2

以下内容适用于您的数据。它使用您的GROUP BY 查询作为DELETE 的子查询：

DELETE V FROM  
@Visitor AS v
JOIN 
(
  SELECT
    RegDate,
    MIN(Visitors) MinVisitors,
    MAX(Visitors) MaxVisitors
  FROM
    @Visitor AS V
  GROUP BY
    RegDate
) T  ON 
  v.RegDate = T.RegDate 
  AND V.Visitors <> T.MinVisitors 
  AND V.Visitors <> T.MaxVisitors