SQL查询使用CASE WHEN来转动列

Question

我有下表:

Bank:
name  val   amount
John   1     2000
Peter  1     1999
Peter  2     1854
John   2     1888

我正在尝试编写SQL查询以提供以下结果:

name  amountVal1 amountVal2  
John    2000        1888   
Peter   1999        1854    

到目前为止我有这个:

SELECT name,
CASE WHEN val = 1 THEN amount ELSE 0 END AS amountVal1,
CASE WHEN val = 2 THEN amount ELSE 0 END AS amountVal2
FROM bank

但是,它给出了稍微错误的结果:

name  amountVal1 amountVal2  
John    2000        0
Peter   1999        0
John    0          1888   
Peter   0          1854    

如何修改我的查询以提供正确的演示文稿？谢谢

Answer 1

SELECT 
  name,
  SUM(CASE WHEN val = 1 THEN amount ELSE 0 END) AS amountVal1,
  SUM(CASE WHEN val = 2 THEN amount ELSE 0 END) AS amountVal2
FROM bank GROUP BY name