获取记录日期时间字段值作为结果列的 SQL 语句

Question

我有以下两张表

activity(activity_id, title, description, group_id)
statistic(statistic_id, activity_id, date, user_id, result)

group_id 和 user_id 来自活动目录。结果是一个整数。

给定一个 user_id 和 6 天（周一至周六）的日期范围，这是我在业务逻辑方面计算得出的，并且该日期范围内的某些日期可能没有特定日期的统计结果日期（即第 1 天和第 4 天可能已输入特定活动的统计行，但第 2、3、5 和 6 天可能没有任何条目）如何获得具有以下格式的 SQL 结果？请记住，如果特定活动在统计表中没有特定日期的记录，则该日期应在 SQL 结果中返回 0。

activity_id    group_id    day1result    day2result    day3result    day4result    day5result    day6 result
-----------    --------    ----------    ----------    ----------    ----------    ----------    -----------
sample1        Secured     0             5             1             0             2             1
sample2        Unsecured   1             0             0             4             3             2

注意：目前我正计划在业务逻辑中处理此问题，但这需要多个查询（一个为该用户在日期范围内创建不同活动的列表，一个为每个活动在每个日期循环结果或缺少结果，用与日期相关的结果填充数组的第二维）。这可能会导致每个日期范围内的每个用户有 50 多个查询，这对我来说似乎有点过头了。

我让它工作了 4 天，我可以让它工作 6 天，但这似乎有点矫枉过正。有没有办法简化这个？：

SELECT d1d2.activity_id, ISNULL(d1d2.result1,0) AS day1, ISNULL(d1d2.result2,0) AS day2, ISNULL(d3d4.result3,0) AS day3, ISNULL(d3d4.result4,0) AS day4
FROM
    (SELECT ISNULL(d1.activity_id,0) AS activity_id, ISNULL(result1,0) AS result1, ISNULL(result2,0) AS result2
     FROM
         (SELECT ISNULL(statistic_result,0) AS result1, ISNULL(activity_id,0) AS activity_id
          FROM statistic 
              WHERE user_id='jeremiah' AND statistic_date='11/22/2011'
          ) d1
          FROM JOIN
          (SELECT ISNULL(statistic_result,0) AS result2, ISNULL(activity_id,0) AS activity_id
           FROM statistic WHERE user_id='jeremiah' AND statistic_date='11/23/2011'
          ) d2
          ON d1.activity_id=d2.activity_id
     ) d1d2
     FULL JOIN
     (SELECT d3.activity_id AS activity_id, ISNULL(d3.result3,0) AS result3, ISNULL(d4.result4,0) AS result4
      FROM
          (SELECT ISNULL(statistic_result,0) AS result3, ISNULL(activity_id,0) AS activity_id
           FROM statistic WHERE user_id='jeremiah' AND statistic_date='11/24/2011'
          ) d3
          FULL JOIN
          (SELECT ISNULL(statistic_result,0) AS result4, ISNULL(activity_id,0) AS activity_id
           FROM statistic WHERE user_id='jeremiah' AND statistic_date='11/25/2011'
          ) d4
          ON d3.activity_id=d4.activity_id
     ) d3d4
     ON d1d2.activity_id=d3d4.activity_id
ORDER BY d1d2.activity_id

Answer 1

这是处理这类事情的典型方法：

DECLARE @minDate DATETIME,
        @maxdate DATETIME,
        @userID VARCHAR(200)

SELECT  @minDate = '2011-11-15 00:00:00',
        @maxDate = '2011-11-22 23:59:59',
        @userID = 'jeremiah'

SELECT A.activity_id, A.group_id, 
        SUM(CASE WHEN DATEDIFF(day, @minDate, S.date) = 0 THEN S.Result ELSE 0 END) AS Day1Result,
        SUM(CASE WHEN DATEDIFF(day, @minDate, S.date) = 1 THEN S.Result ELSE 0 END) AS Day2Result,
        SUM(CASE WHEN DATEDIFF(day, @minDate, S.date) = 2 THEN S.Result ELSE 0 END) AS Day3Result,
        SUM(CASE WHEN DATEDIFF(day, @minDate, S.date) = 3 THEN S.Result ELSE 0 END) AS Day4Result,
        SUM(CASE WHEN DATEDIFF(day, @minDate, S.date) = 4 THEN S.Result ELSE 0 END) AS Day5Result,
        SUM(CASE WHEN DATEDIFF(day, @minDate, S.date) = 5 THEN S.Result ELSE 0 END) AS Day6Result
FROM activity A 
    LEFT OUTER JOIN statistic S 
        ON A.activity_id = S.activity_ID
            AND S.user_id = @userID
WHERE S.date between @minDate AND @maxDate 
GROUP BY A.activity_id, A.group_id 

首先，我使用group by 将结果集减少到每个activity_id/group_id 一行，然后我使用CASE 来分隔每个单独列的值。在这种情况下，我正在查看过去七日中的哪一天，但您可以使用那里的任何逻辑来确定日期。如果该行是针对特定日期的，case 语句将返回 S.result 的值，否则返回 0。 SUM 将添加单个值（或仅一个，如果只有一个）并将其合并到一行中。

您还会注意到，我的日期范围基于该范围第一天的午夜和该范围最后一天的晚上 11:59，以确保所有时间都包含在该范围内。

最后，我正在执行左连接，因此即使没有统计信息，您的列中也将始终为 0。

Answer 2

除了活动之外，我不完全确定您的结果是如何按组划分的（除非组是更高级别的构造），但这是我将采取的方法：

   SELECT activity_id
          day1result = SUM(CASE DATEPART(weekday, date) WHEN 1 THEN result ELSE 0 END)
     FROM statistic
GROUP BY activity_id

我将把剩下的日子和 group_id 的添加留给你，但你应该看看一般的方法。