Question

如何更改此表

Name      subject     Mark
Aswin     physics     100
Aswin     chemistry   300
Aswin     maths       200

向

Aswin Physics 100 Chemistry 300 Maths 200

任何人请帮帮我。

Answer 1

你可以使用PIVOT操作符在sql server中完成这项工作。

检查这些链接link1和link2他们将展示如何将行更改为列。

希望这可以帮到你！

Answer 2

SQLFiddle demo

select Name,
       sum(CASE 
          when [subject]='physics' then Mark
       end) as Physics,
       sum(CASE 
          when [subject]='chemistry' then Mark
       end) as chemistry,
       sum(CASE 
          when [subject]='maths' then Mark
       end) as maths


from t group by Name

或者如果您需要一行：

SQLFiddle demo

SELECT
   t1.name,
   MemberList = substring((SELECT ( ', ' + subject+' - '+
                                   cast(Mark as varchar(100)) )
                           FROM t t2
                           WHERE t1.name = t2.name
                           ORDER BY 
                              name,
                              subject
                           FOR XML PATH( '' )
                          ), 3, 1000 )FROM t t1
GROUP BY name

Answer 3

您需要使用SQL Pivoting，请查看SQL SERVER – PIVOT and UNPIVOT Table Examples处的示例。使用Sql Pivoting可以将行更改为列，而Unpivoting则用于列到行的转换。

请注意：我正在检查我是否能为您提供确切的脚本，但现在该链接可以帮助您。

更新

代码示例
虽然我没有用实际数据对此进行测试，但它解析得很好。

-- Pivot Table ordered by Name of Student
SELECT Name, Physics, Chemistry, Maths
FROM (
SELECT Name, Subject, Mark
FROM Student) up
PIVOT (SUM(Mark) FOR Student IN (Physics, Chemistry, Maths)) AS pvt
ORDER BY Name

-- Result should be something like
----------------------------------
Name   Physics   Chemistry   Maths
----------------------------------
Aswin  100       300         200

----------------------------------

要创建数据透视，您需要知道要转换为列的实际行值。我之前写过关于动态旋转here的文章，如果你发现它有用的话。

Answer 4

目前尚不清楚您是希望将这些数据放在单独的列中还是列在一列中。

如果您希望在单独的列中进行此操作，则可以应用SQL Server 2005中可用的PIVOT函数。

如果您知道要转换的所有值或数量有限的值，那么您可以对查询进行硬编码：

select *
from
(
  select name, subject +' '+ cast(mark as varchar(9)) as sub_mark,
    'Subject_'+cast(row_number() over(partition by name 
                                     order by subject) as varchar(10)) col_name
  from subjects
) s
pivot
(
  max(sub_mark)
  for col_name in (Subject_1, Subject_2, Subject_3)
) piv;

见SQL Fiddle with Demo。您会注意到我与其他 pivot 答案略有不同。我将主题/标记放在同一列中，列名为Subject_1等。

如果您有不确定数量的值，则可以使用动态sql：

DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT distinct ',' + QUOTENAME('Subject_'+cast(row_number() over(partition by name 
                                     order by subject) as varchar(10))) 
                    from subjects
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT name,' + @cols + ' from 
             (
                select name, subject +'' ''+ cast(mark as varchar(9)) as sub_mark,
                  ''Subject_''+cast(row_number() over(partition by name 
                                                   order by subject) as varchar(10)) col_name
                from subjects
            ) x
            pivot 
            (
              max(sub_mark)
              for col_name in (' + @cols + ')
            ) p '

execute(@query)

见SQL Fiddle with Demo。如果name有超过3个主题，动态sql版本的列数会增加。

两个查询的结果是：

|  NAME |     SUBJECT_1 | SUBJECT_2 |   SUBJECT_3 |
---------------------------------------------------
| Aswin | chemistry 300 | maths 200 | physics 100 |

如何将行更改为列？

4 个答案:

更新