mysql - 数据库行需要包含列

Question

我有一个下面的 MySQL 表。

id       Creation_Date         Goals  Alternative    Value
-----------------------------------------------------------
1   2014-04-17 10:09:30     G1      A        0.86
2   2014-04-17 10:09:30     G1      B        0.87
3   2014-04-17 10:09:30     G2      A        0.5
4   2014-04-17 10:09:30     G2      B         0

我需要一个 MySQL 查询来更改列中的行，并且还需要它们各自的值，如下所示。

**输出要求**

Alternative     G1         G2  
------------------------------- 
   A           0.86        0.50
   B           0.87        0

尝试过的解决方案:

我尝试了以下查询

select Alternative , max(case when Goals = 'G1' then round(value,2) end) as Goal1, max(case when Goals = 'G2' then round(value,2) end) as Goal2 from sgwebdb.dim_module group by id ; 

但这没有给出所需的输出，这给出了以下输出

Alternative     G1         G2  
------------------------------- 
   A         0.86         Null
   B         0.87         Null
   A     Null         0.50
   B     Null         0.00

Answer 1

尝试这个查询:

SELECT Alternative,
SUM(Val*(1-ABS(SIGN(Goals-1)))) AS G1,
SUM(Val*(1-ABS(SIGN(Goals-2)))) AS G2
FROM table1 
GROUP BY Alternative;

表格如下所示:将G1更改为1并将G2更改为2

id       Creation_Date     Goals  Alternative    Value
-----------------------------------------------------------
1    2014-04-17 10:09:30       1        A             0.86
2    2014-04-17 10:09:30       1        B             0.87
3    2014-04-17 10:09:30       2        A             0.5
4    2014-04-17 10:09:30       2        B             0

结果如下:

Alternative     G1         G2  
------------------------------- 
   A           0.86        0.50
   B           0.87        0