sql - 将不同的行属性转置/旋转为列并将另一个属性分组？

Question

可能重复：
SQL Server 动态 PIVOT 查询？

是否可以对下表执行查询：

Game    Player  Goals
-----   ------  ------
Game1   John    1
Game1   Paul    0
Game1   Mark    2
Game1   Luke    1
Game2   John    3
Game2   Paul    1   
Game2   Luke    1
Game3   John    0
Game3   Mark    2

这给出了这样的结果：

Game    John    Paul    Mark    Luke
-----   ----    ----    ----    ----
Game1   1       0       2       1
Game2   3       1       -       1
Game3   0       -       2       -

它将每个不同的玩家变成一列，并将游戏分组，为每位玩家提供每场比赛的目标。

Answer 1

您可以使用该PIVOT功能。如果您有已知数量的列，则可以对这些值进行硬编码：

select *
from
(
  select game, player, goals
  from yourtable
) src
pivot
(
  sum(goals)
  for player in ([John], [Paul], [Mark], [Luke])
) piv
order by game

请参阅带有演示的 SQL Fiddle

如果您有未知数量的列，那么您可以使用动态 sql：

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

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(player) 
                    from yourtable
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT game, ' + @cols + ' from 
             (
                select game, player, goals
                from yourtable
            ) x
            pivot 
            (
                sum(goals)
                for player in (' + @cols + ')
            ) p '

execute(@query)

请参阅带有演示的 SQL Fiddle

Answer 2

select game,
  sum(case when player = 'john' then goals else 0 end) as john,
  sum(case when player = 'paul' then goals else 0 end) as paul,
  sum(case when player = 'mark' then goals else 0 end) as mark,
  sum(case when player = 'luke' then goals else 0 end) as luke
from t
group by game
order by game