Question

我有一个表（ClassEnrolments），其中包含学生数据：

StudentId       Student        Module          Status      EndDate         Credits
12345678        J Bloggs       Introduction    Pass        2014/09/01      10
12345678        J Bloggs       Advanced        Pass        2014/06/01      15
23456789        T Guy          Introduction    Pass        2013/05/25      10
23456789        T Guy          Advanced        Pass        2014/03/21      15

我想要做的是返回学生在一段时间内总共采取了多少模块的信息，例如，如果我们采用上述数据并查看01/01/2014至24期间/ 11/2014它将返回以下内容（基于EndDate）

StudentId        Student        Modules      Credits      AnnivDate
12345678         J Bloggs       2            25           2015/06/01
23456789         T Guy          1            15           2014/05/25

这是使用SQL Server 2008 - 非常感谢任何帮助。

我现在也想知道是否使用相同的场景 - 是否可以计算从这些模块中获得的学分数？

另一个想法！根据学生最重要的模块，看一些周年纪念日会很有用。这将有助于确定学生是否在周年日之前获得了正确的学分。我已经玩弄了DATEADD功能的想法，但这似乎又重复了学生的信息。

DATEADD(MONTH, DATEDIFF(MONTH, 0, EndDate()) +12,0) AS AnnivDate

我理解为什么，因为会有多个实例，但有没有办法查看EndDate的第一个实例？

Answer 1

试试这个：

Set dateformat DMY;
Select StudentId, Student, Count(Modules) as ModuleCount
from ClassEnrolments 
Where EndDate >= convert(Datetime, '01-01-2014', 105) and 
EndDate <= convert(Datetime, '24-11-2014', 105)
Group By StudentId, Student

Answer 2

试试这个：

SELECT
   StudentId,
   Student,
   COUNT(*) Modules
FROM ClassEnrolments
WHERE 
   EndDate BETWEEN '2014-01-01' AND '2014-11-24'
GROUP BY 
   StudentId,
   Student

Answer 3

SELECT StudentID, Student, Count(module) AS Modules
FROM ClassEnrolments
GROUP BY StudentID, Student

日期

SELECT StudentID, Student, Count(module) AS Modules
FROM ClassEnrolments
WHERE EndDate BETWEEN '2014-01-01' AND '2014-11-24'
GROUP BY StudentID, Student

Answer 4

使用Group By和汇总功能count计算Module并使用Between operator过滤特定日期范围之间的数据来过滤数据

SELECT StudentId,
       Student,
       Count(Module) Module,
       Sum(Credits) Credits
FROM   tablename
WHERE  EndDate BETWEEN '2014-01-01' AND '2014-11-24'
GROUP  BY StudentId,
          Student

Answer 5

SELECT
   StudentId,Student,COUNT(*)
FROM TableName
WHERE EndDate BETWEEN '2014-01-01' AND '2014-11-24'
AND Status = 'Pass'
GROUP BY StudentId,Student

Answer 6

实际上并不是你要求的，但可能是另一种选择，具体取决于你想要的东西。

DECLARE @ClassEnrollments
TABLE   (
        StudentId   INT
        ,Student    VARCHAR(50)
        ,Module     VARCHAR(50)
        ,Status     VARCHAR(50)
        ,EndDate    DATE
        )

INSERT
INTO    @ClassEnrollments

VALUES   (12345678,'J Bloggs','Introduction','Pass','2014/09/01')
        ,(12345678,'J Bloggs','Advanced','Pass','2014/06/01')
        ,(23456789,'T Guy','Introduction','Pass','2013/05/25') -- Excluded
        ,(23456789,'T Guy','Advanced','Pass','2014/03/21')


SELECT  StudentId   
        ,Student    
        ,Module     
        ,Status     
        ,EndDate    
        ,COUNT(Module) OVER (PARTITION BY studentId) as #Modules
FROM    @ClassEnrollments
WHERE   EndDate 
        BETWEEN '2014-01-01' 
        AND     '2014-11-24'
ORDER BY
        StudentId
        ,Module

SQL到COUNT项与个人关联的项目

6 个答案: