Question

我正在尝试从任务的项目和组中获取最新的结束日期（ProjectsTasksEndDate），但没有成功。 Bellow是SQLFiddle。有什么建议吗？

PS：评论的选择是构建我想要的选择的基础。

MS SQL Server 2008架构设置：

CREATE TABLE Projects 
(
  id int identity primary key, 
  ProjectID varchar(20),
  ProjectStartDate date,
  ProjectEndDate date
 );

CREATE TABLE ProjectsTasks 
(
  id int identity primary key, 
  ProjectID varchar(20), 
  ProjectsTasksStartDate date,
  ProjectsTasksEndDate date
 );

INSERT INTO Projects
(ProjectID, ProjectStartDate, ProjectEndDate)
VALUES
('1', '2015-01-05', '2015-04-08'),
('2', '2015-01-06', '2015-07-20'),
('3', '2015-02-05', '2015-07-22'),
('4', '2015-03-05', '2015-08-08'),
('5', '2015-03-05', '2015-09-18'),
('6', '2015-04-05', '2015-10-02'),
('7', '2016-07-05', '2016-11-20');

INSERT INTO ProjectsTasks
(ProjectID, ProjectsTasksStartDate, ProjectsTasksEndDate)
VALUES
('1', '2015-01-05', '2015-01-10'),
('1', '2015-01-06', '2015-02-20'),
('1', '2015-02-05', '2015-03-20'),
('1', '2015-03-01', '2015-03-02'),
('1', '2015-01-05', '2015-04-08'),
('2', '2015-06-01', '2015-06-20'),
('3', '2015-12-20', '2015-12-21');

查询1 ：

/*
SELECT
    YEAR (Projects.ProjectEndDate) AS [Year],
    MONTH (Projects.ProjectEndDate) AS [Month],
    COUNT (*) AS [Total]
FROM
    Projects
GROUP BY
    YEAR (Projects.ProjectEndDate),
    MONTH (Projects.ProjectEndDate)
*/


SELECT
    YEAR (MAX(ProjectsTasks.ProjectsTasksEndDate)) AS [Year],
    MONTH (MAX(ProjectsTasks.ProjectsTasksEndDate)) AS [Month],
    COUNT (*) AS [Total]
FROM  Projects 
RIGHT JOIN ProjectsTasks  
  ON Projects.ProjectID = ProjectsTasks.ProjectID
GROUP BY  YEAR (ProjectsTasks.ProjectsTasksEndDate),
          MONTH (ProjectsTasks.ProjectsTasksEndDate)

[预期结果] ：

| Year | Month | Total |
|------|-------|-------|
| 2015 |     4 |     1 |
| 2015 |     6 |     1 |
| 2015 |    12 |     1 |

Answer 1

如果我理解你的意图，你可以使用：

SELECT TOP 1 
     [Year]  = YEAR(ProjectsTasks.ProjectsTasksEndDate)
    ,[Month] = MONTH(ProjectsTasks.ProjectsTasksEndDate)
    ,[Total] = COUNT (*)
FROM  Projects 
RIGHT JOIN ProjectsTasks  
  ON Projects.ProjectID = ProjectsTasks.ProjectID
GROUP BY YEAR(ProjectsTasks.ProjectsTasksEndDate),
         MONTH(ProjectsTasks.ProjectsTasksEndDate)
ORDER BY Year DESC, Month DESC

的 LiveDemo

修改

SELECT TOP 1 WITH TIES [Year],[Month],[Total] FROM ( SELECT ProjectsTasks.ProjectID ,[Year] = YEAR(MAX(ProjectsTasks.ProjectsTasksEndDate)) ,[Month] = MONTH(MAX(ProjectsTasks.ProjectsTasksEndDate)) ,[Total] = COUNT (*) FROM Projects RIGHT JOIN ProjectsTasks ON Projects.ProjectID = ProjectsTasks.ProjectID GROUP BY ProjectsTasks.ProjectID, YEAR(ProjectsTasks.ProjectsTasksEndDate), MONTH(ProjectsTasks.ProjectsTasksEndDate) ) s ORDER BY ROW_NUMBER() OVER(PARTITION BY ProjectID ORDER BY [Year] DESC, [Month] DESC);

的 LiveDemo 2

输出：

╔══════╦═══════╦═══════╗ ║ Year ║ Month ║ Total ║ ╠══════╬═══════╬═══════╣ ║ 2015 ║ 4 ║ 1 ║ ║ 2015 ║ 6 ║ 1 ║ ║ 2015 ║ 12 ║ 1 ║ ╚══════╩═══════╩═══════╝

使用MAX（）分组

1 个答案: