Question

我将举两个例子，第一个有效，第二个有我想做的事：

SELECT P.ProjName, D.update_date, SUM(E.pass), SUM(E.fail)
  FROM execution AS E INNER JOIN ( 
    daily AS D INNER JOIN project AS P ON D.project_ID = P.ID )
    ON E.daily_ID = D.ID
  WHERE D.project_id = 25 AND D.update_date = ( 
    SELECT MAX(update_date) FROM daily WHERE project_id = 25; )
  GROUP BY P.ProjName, D.update_date;

这适用于个别项目。它给出了给定项目最近一天的通过和失败总数（此处为25）。我想使用WHERE IN子句获取一组项目。例如（但不起作用）：

SELECT P.ProjName, D.update_date, SUM(E.pass), SUM(E.fail)
  FROM execution AS E INNER JOIN ( 
    daily AS D INNER JOIN project AS P ON D.project_ID = P.ID )
    ON E.daily_ID = D.ID 
  WHERE D.project_id IN (25,26,28,29,30,31)
  GROUP BY P.ProjName, D.update_date
  HAVING MAX(D.update_date);

这将导致每个项目的每个日期都被拉出。涉及3个表，'project'由'daily'链接，由'execution'链接。因此，对于每个项目，每天都有多个数据，每天都有多个执行数据。我意识到HAVING MAX可能需要进行比较，但对于什么？也许修改后的JOIN会有所帮助。

谢谢，基思

Answer 1

在不知道数据库的情况下尝试这样做有点棘手，但试试这个：

SELECT P.ProjName, D.update_date, SUM(E.pass), SUM(E.fail)
  FROM execution AS E INNER JOIN ( 
    daily AS D INNER JOIN project AS P ON D.project_ID = P.ID )
    ON E.daily_ID = D.ID
  WHERE D.project_id IN (25,26,28,29,30,31) AND D.update_date = ( 
    SELECT MAX(update_date) FROM daily WHERE project_id = D.project_id)
  GROUP BY P.ProjName, D.update_date;

我真的不知道这是否接近你想要的任何东西。

Answer 2

您没有指定特定的DBMS，那么这个（未经测试的）SQL代码应该在多大程度上与DBMS无关：

SELECT P.ProjName, 
       DesiredProjectUpdateDate.MaxUpdateDate, 
       SELECT SUM(pass) AS PassSum 
       FROM execution 
       WHERE daily_ID=D.ID,
       SELECT SUM(fail) AS FailSum 
       FROM execution 
       WHERE daily_ID=D.ID
FROM
( -- This derived table helps you get the correct records from the daily table
  SELECT D.project_ID, MAX(D.Update_date) AS MaxUpdateDate 
  FROM daily AS D
  GROUP BY D.project_ID
  WHERE D.project_ID IN (25,26,28,29,30,31)
) As DesiredProjectUpdateDate
JOIN daily AS D
  ON D.project_ID=DesiredProjectUpdateDate.project_ID AND
     D.Update_date=DesiredProjectUpdateDate.MaxUpdateDate
JOIN project AS P
  ON P.ID = DesiredProjectUpdateDate.ProjectId

如果你有任何进一步的问题，请告诉我们。

Answer 3

问题是您需要一个select，它返回每个项目的update_date的最大值。

试试这个：

SELECT P.ProjName, D.update_date, SUM(E.pass), SUM(E.fail)
  FROM execution AS E INNER JOIN ( 
    daily AS D INNER JOIN project AS P ON D.project_ID = P.ID )
    ON E.daily_ID = D.ID 
  WHERE D.project_id IN (25,26,28,29,30,31)
  AND D.update_date > ALL
  (SELECT update_date FROM
   daily AS D2
   WHERE D.ID=D2.ID -- I am assuming that daily.ID is the primary key
   AND ISNULL(D.update_date, '9999 DEC 31') <> D2.update_date)
  GROUP BY P.ProjName, D.update_date;

我经常写这样的查询，它们比使用MAX聚合函数更快并且工作得很好。

编辑：抱歉，我忘记删除您现在多余的HAVING MAX...行。我的坏！

SQL MAX日期与WHERE IN子句

3 个答案: