mysql如何實作行轉列

mysql實現行轉列的方法：1、用cross join的方式實現，程式碼為【cross join(select sum(a.kills) '豬八戒】；2、用case語句的方式實現，程式碼為【case when user_name='孫悟空'】。

#本教學操作環境：windows7系統、mysql8.0.22版，此方法適用於所有品牌電腦。

mysql實作行轉列的方法：

1、用cross join的方式實作

select * from 
(select sum(a.kills) '孙悟空' 
  from kills1 as a 
  LEFT JOIN tssrz as b 
    on a.user_id = b.id 
 WHERE b.user_name = '孙悟空' 
 GROUP BY b.user_name) e
 cross join 
 (select sum(a.kills) '猪八戒' 
  from kills1 as a 
  LEFT JOIN tssrz as b 
    on a.user_id = b.id 
 WHERE b.user_name = '猪八戒' 
 GROUP BY b.user_name) f

2.用case語句的方式實作

SELECT sum(case when user_name='孙悟空' then kills end) as '孙悟空',
  sum(case when user_name='猪八戒' then kills END) as '猪八戒',
  sum(case when user_name='沙和尚' then kills END) as '沙和尚'
   from tssrz as a
   join kills1 as b
     on a.id = b.user_id

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