当我不想使用聚合时,是否应该使用Pivot将SQL Server 2008行值转换为列名？

我试图掌握将表数据操作为更具视觉吸引力的输出格式.这可能是问题的一部分,因为我想要的可能是用于单独的报告软件.

我有一张看起来像这样的桌子

teacher    student
----------------------
teacher1   Bob
teacher1   Jim
teacher2   Sam
teacher3   Bill
teacher3   John
teacher3   Eric

我想要一个看起来像这样的表：

teacher1    teacher2    teacher3
---------------------------------
Bob         Sam          Bill
Jim         null         John
null        null         Eric

所以我尝试在变量中填充所有教师名称,然后使用Pivot,但由于我必须选择聚合,所以我只能得到这样的Max或Min学生：

DECLARE @teacherList AS VARCHAR(max)

SELECT @teacherList = Stuff((SELECT disTINCT',[' + teacher + ']'
                              FROM myTable
                              FOR xml path('')),1,'')

DECLARE @dynamic_pivot_query AS VARCHAR(max)

SET @dynamic_pivot_query = 'select' + @teacherList + 
'from 
(
    SELECT [teacher],[student]
    FROM [dbo].[myTable]
) as S
Pivot
(
    MIN([student])
    FOR teacher IN (' + @teacherList + ')
) as P
'
EXEC(@dynamic_pivot_query)

结果是：

teacher1    teacher2    teacher3
---------------------------------
Bob         Sam          Bill

假设如下：

>教师#及其姓名未知(可变)
>每位教师的学生人数不详,每位教师可能也不同

有没有办法做到这一点？

解决方法

您可以使用row_number来获得所需的结果.

SET @dynamic_pivot_query = 'select ' + @teacherList + 
'from 
(
    SELECT [teacher],[student],row_number() over(partition by teacher order by student) as rn
    FROM [dbo].[myTable]
) as S
Pivot
(
    MIN([student])
    FOR teacher IN (' + @teacherList + ')
) as P
'

更新：
要删除sql注入漏洞,您应该使用引号来正确引用您的字段列表.

SELECT @teacherList = Stuff((SELECT disTINCT',' + quotename(teacher)
                              FROM myTable
                              FOR xml path('')),'')