SQL 使用 PIVOT 权

Question

我有一个问题，我正在尝试在我的查询中使用 PIVOT 但没有任何结果。现在我有一个 table 看起来像：

Category     Month    Value
A            August     10
B            August     19
C            August     15
A            September  20
B            September  23
C            September  25
A            October    24
B            October    87
C            October    44

我想做成这样：

Category      August       September    October
      A       10             20          24
      B       19             23          87
      C       15             25          47

在我的 select 中是这样的：

Select cat_name, CAST(month AS VARCHAR(20)), value from dbo.table1.

_

      select * from (
        select ft.categoryData as [category], CAST(fft.date AS VARCHAR(20)) as [month], tt.value as [value] from firstt ft
                join secondt st on ft.id = st.id
                join thirdt tt on ft.id = tt.type_id
                join fourtht fft on ft.id = fft.category_id
            where ft.date between '2015-07-01' and '2015-09-01' and ft.country = 'EUR'  
group by fft.date, ft.categoryData, tt.value
                ) as t

        PIVOT (

    max(value)
    for [date] in ([jul], [aug], [sept])


      ) as pvt

Answer 1

尝试Conditional Aggregate。

select Category,
       max(case when Month = 'August' then Value END) as August,
       max(case when Month = 'September' then Value END) as September,
       max(case when Month = 'October' then Value END) as October
from Yourtable
Group by Category

SQL FIDDLE DEMO

或使用Pivot

select * 
from Yourtable
pivot (max(Value) For Month in ([August],[September],[October]))pv

SQL FIDDLE DEMO

当月份列中的值未知时使用动态 sql

 declare @sql nvarchar(max)= '',
         @col_list varchar(max)=''

 set @col_list =(select distinct quotename(Month)+',' from yourtable for xml path (''))
 set @col_list  = left(@col_list,len(@col_list)-1)
 set @sql  = '
    select * 
    from yourtable
    pivot (max(Value) For Month in ('+@col_list+'))pv'

    exec sp_executesql @sql

SQL FIDDLE DEMO

Answer 2

通过使用 pivot 我们可以编写下面的查询，语法遵循下面的 link 如前所述

https://www.simple-talk.com/sql/t-sql-programming/questions-about-pivoting-data-in-sql-server-you-were-too-shy-to-ask/

SELECT *
FROM TABLE_NAME
PIVOT(MAX(VALUE) FOR MONTH IN (
            [AUGUST]
            ,[SEPTEMBER]
            ,[OCTOBER]
            )) AS
PIVOT_SALES

输出是

>

Answer 3

你可以使用下面的代码

SELECT * from (SELECT Category, Month, Value 
FROM table1 t) pivot (sum (Value) for Month in ('August', 'September', October') ) order by Category;

SQL 使用 PIVOT 权

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