使用 SQL 服务器 NTILE 函数

Question

我正在使用 CTE select 一组记录。从下面的代码中可以看出，我根据学生的成绩分配分数。使用此 CTE，我需要将一组记录插入满足以下条件的 SourceStudentRiskFactor table。按 fst.ClassKey 分组；对于每个组，select 记录 Sum(Points) 位于第三个四分位数（对于 ntile(4)）。任何示例将不胜感激。

with AtRiskBarExam as (
    select
        fr.PersonalIdentifier,
        fr.StudentLevelKey,
        dimGrade.SourceKey,
        case 
            when dimGrade.SourceKey = 'A' then 2
            when dimGrade.SourceKey = 'B' then 1
            when dimGrade.SourceKey = 'C' then 0.5
            else 0
        end AS Points
    from
        Final.FactRegistration fr
        inner join  Final.DimTerm dimTerm
            on  dimTerm.TermKey = fr.TermKey and
                fr.VersionKey = 1
        inner join  Final.DimGrade dimGrade
            on  dimGrade.GradeKey = fr.GradeKey 
        inner join Final.DimStudentLevel dimStudentLevel
            on dimStudentLevel.StudentLevelKey = fr.StudentLevelKey and
            dimStudentLevel.SourceKey = 'GR'
    group by
        fr.PersonalIdentifier,
        fr.StudentLevelKey,
        dimGrade.SourceKey
)

insert into Stage.SourceStudentRiskFactor(
        PersonalIdentifier,
        StudentLevelCode,
        StudentTermCode,
        RiskFactorCode)
    select
        fst.PersonalIdentifier,
        fst.StudentLevelCode,
        fst.StudentTermCode,
        'AtRiskBarExam'
    from
        Final.FactStudentTerm fst
        inner join  Final.DimTerm dimTerm
            on  dimTerm.TermKey = fst.TermKey and
                dimTerm.IncludeTermInLoad = 1 and
                fst.VersionKey = 1
        inner join  AtRiskBarExam e
            on  fst.PersonalIdentifier = e.PersonalIdentifier and
                fst.StudentLevelKey = e.StudentLevelKey
        inner join final.DimClass dimClass
            on dimClass.ClassKey = fst.ClassKey

Answer 1

我更改了样本数据，使我更容易理解。别担心，由于我没有更改列名，它应该仍然适用于您的 CTE。

WITH YourCte
AS
(
    SELECT  'Student1' AS PersonalIdentifier, 7 as TotalPoints, 'Class1' as MaxClassKey
    UNION ALL
    SELECT 'Student2',1,'Class1'
    UNION ALL
    SELECT 'Student3',3,'Class1'
    UNION ALL
    SELECT 'Student4',6,'Class1'
    UNION ALL
    SELECT 'Student5',3,'Class1'
    UNION ALL
    SELECT 'Student6',4,'Class1'
    UNION ALL
    SELECT 'Student7',9,'Class1'
    UNION ALL
    SELECT 'Student8',1,'Class1'
    UNION ALL
    SELECT 'Student9',1,'Class2'
    UNION ALL
    SELECT 'Student10',3,'Class2'
    UNION ALL
    SELECT 'Student11',6,'Class2'
    UNION ALL
    SELECT 'Student12',3,'Class2'
    UNION ALL
    SELECT 'Student13',4,'Class2'
    UNION ALL
    SELECT 'Student14',9,'Class2'
    UNION ALL
    SELECT 'Student15',1,'Class2'
    UNION ALL
    SELECT 'Student16',1,'Class2'
)

SELECT  *,
        --Partition causes NTILE() to look at the classes as individual groups
        NTILE(4) OVER (PARTITION BY MaxClassKey ORDER BY TotalPoints) ClassQuartile
FROM YourCte

结果：

PersonalIdentifier TotalPoints MaxClassKey ClassQuartile
------------------ ----------- ----------- --------------------
Student2           1           Class1      1
Student8           1           Class1      1
Student5           3           Class1      2
Student3           3           Class1      2
Student6           4           Class1      3
Student4           6           Class1      3
Student1           7           Class1      4
Student7           9           Class1      4
Student9           1           Class2      1
Student15          1           Class2      1
Student16          1           Class2      2
Student12          3           Class2      2
Student10          3           Class2      3
Student13          4           Class2      3
Student11          6           Class2      4
Student14          9           Class2      4

使用 SQL 服务器 NTILE 函数

using SQL Server NTILE function

sql

sql-server

tsql

common-table-expression