SQL Server 2008:将列值转换为行

Question

我有一个表格,格式如下

Country_Code | 1960 | 1961 | 1962 | ..... | 2011
------------------------------------------------
IND          | va11 | va12 | va13 | ..... | va1x
AUS          | va21 | va22 | va23 | ..... | va2x
ENG          | va31 | va32 | va33 | ..... | va3x

我想将其转换为以下格式

Country_Code | Year | Value
---------------------------
IND          | 1960 | va11
IND          | 1961 | va12
IND          | 1962 | va13
.
.
IND          | 2011 | va1x
AUS          | 1960 | va21
AUS          | 1961 | va22
AUS          | 1962 | va23
.
.
AUS          | 2011 | va2x
ENG          | 1960 | va31
ENG          | 1961 | va32
ENG          | 1962 | va33
.
.
ENG          | 2011 | va3x

如何通过SQL查询或SQL Server程序集来实现？

Answer 1

你可以完成UNPIVOT.如果您有已知数量的列,则可以对值进行硬编码:

select Country_Code, year, value
from yourtable
unpivot
(
  value 
  for year in ([1960], [1961], [1962], [2011])
) u

请参阅SQL Fiddle with Demo

如果您有未知数量的列,那么您可以使用动态sql:

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

select @colsUnpivot = stuff((select ','+quotename(C.name)
         from sys.columns as C
         where C.object_id = object_id('yourtable') and
               C.name != 'Country_Code'
         for xml path('')), 1, 1, '')

set @query 
  = 'select country_code, year, value
     from yourtable
     unpivot
     (
        value
        for year in ('+ @colsunpivot +')
     ) u'

exec(@query)

请参阅SQL Fiddle with Demo

你甚至可以使用UNION ALL:

select country_code, '1960' year, 1960 value
from yourtable
union all
select country_code, '1961' year, 1961 value
from yourtable
union all
select country_code, '1962' year, 1962 value
from yourtable
union all
select country_code, '2011' year, 2011 value
from yourtable

请参阅SQL Fiddle with Demo