Question

与我之前发布的另一个问题很相似，但更复杂（我想！）。

我有一组表格：

表1

 StudentId   Student     Course
 1234567     J. Bloggs   ABC      
 1234567     J. Bloggs   ABC       
 2345678     T. Test     ABC

表2

StudentId    Student       Module      Result      StartDate     EndDate
1234567      J. Bloggs     DEF         Fail        13/01/2014    13/03/2014
1234567      J. Bloggs     DEF         Pass        01/05/2014    15/07/2014
2345678      T. Test       DEF         Pass        13/01/2014    13/03/2014

我想要做的是让SQL返回，首先是学生在模块中尝试了多少次尝试，然后返回最新的EndDate和Result，这样的事情

Student     Course    Module      ModuleAttempts       Result       EndDate
J. Bloggs   ABC       ABC               2              Pass         15/07/2014
T. Test     ABC       ABC               1              Pass         13/03/2014

编辑：添加了初始表格布局

Answer 1

这应该做：

;WITH CTE AS
(
    SELECT  *,
            ModuleAttempts = COUNT(*) OVER(PARTITION BY Student, Module),
            RN = ROW_NUMBER() OVER(PARTITION BY Student, Module
                                   ORDER BY EndDate DESC)
    FROM dbo.YourTable
)
SELECT  Student,
        Course,
        Module,
        ModuleAttempts,
        Result,
        EndDate
FROM CTE
WHERE RN = 1;

SQLFIDDLE DEMO

Answer 2

你去了：SQL Fiddle Demo

SELECT Student, Course, Module, 
(SELECT COUNT(*) FROM myTable t2 WHERE t2.Student = t1.Student) as ModuleAttempts, 
CASE WHEN CAST(MAX(CAST(RESULT as INT)) AS BIT) = 1 THEN 'PASS' ELSE 'Fail' END as Result,
MAX(EndDate) as EndDate
FROM MyTable t1
GROUP By Student, Course, Module

注意：

结果是我的示例中的位列（Pass = 1，Failed = 0）
声明： （SELECT COUNT（*）FROM myTable t2 WHERE t2.Student = t1.Student）应为t2.ID = t1.ID，而不是t2.Student = t1.Student。

Answer 3

Lamak的答案是正确的，但由于结果只包含失败并通过以下查询也将有效。

    SELECT  Student,
            Course,
            Module,
           count(ModuleAttempts) as ModuleAttempts,
           max(Result) as Result,
--max(Result) will return "pass" (if pass exists) as it comes after fail in dictionary 
           max(EndDate) as EndDate
    from table
    group by Student,
            Course,
            Module

Answer 4

这是您的示例数据

SELECT * INTO #TEMP FROM
(
SELECT 'J. Bloggs' Student,   'ABC' Course,   '13/01/2014' StartDate,    '13/03/2014' EndDate,     'ABC' Module,       'Fail' Result
UNION ALL
SELECT 'J. Bloggs',   'ABC',       '01/05/2014',    '15/07/2014',     'ABC',        'Pass'
UNION ALL
SELECT 'T. Test',     'ABC',       '13/01/2014',    '13/03/2014',     'ABC' ,       'Pass'
)TAB

现在我已采用StartDate和EndDate对应Student以及Course

SELECT Student,Course,Module,ModuleAttempts,Result,CONVERT(VARCHAR(10),EndDateNew,103) EndDate
FROM
(
    SELECT *,
    ROW_NUMBER() OVER(PARTITION BY STUDENT,Course ORDER BY CAST(CONVERT(CHAR(10),CONVERT(DATETIME,LEFT(ENDDATE,10),105),101) AS DATE) DESC) RNO,
    COUNT(RESULT) OVER(PARTITION BY STUDENT,Course) ModuleAttempts,
    MIN(CAST(CONVERT(CHAR(10),CONVERT(DATETIME,LEFT(StartDate,10),105),101) AS DATE)) OVER(PARTITION BY STUDENT,Course) SD,
    MAX(CAST(CONVERT(CHAR(10),CONVERT(DATETIME,LEFT(ENDDATE,10),105),101) AS DATE)) OVER(PARTITION BY STUDENT,Course) EndDateNew  
    FROM #TEMP 
)TAB
WHERE RNO=1

SQL FIDDLE

如果您还想根据模块选择，请更改

 PARTITION BY STUDENT,Course

到

PARTITION BY STUDENT,Course,Module

<强> RESULT

enter image description here

不同使用COUNT和GROUP

4 个答案: