Question

基本上我有一个这样的专栏：

+----------------+
| Marks          |
+----------------+
|Maths,Phy,Che   |
|Maths,Phy       | 
|Phy,Che         |
|Che             |
|Maths,Phy,Che   |
|Maths,Phy,Che   |
+----------------+

我想成为这样的

+-------------------------+-------+------+------+
| marks                   | Maths | Phy  | Che  |
+-------------------------+-------+------+------+
| Maths,Phy,Che           | 1     | 1    | 1   |
| Maths,Phy               | 1     | 1    | 0   |
| Phy,Che                 | 0     | 1    | 1   |
| Che                     | 0     | 0    | 1   |
| Maths,Phy,Che           | 1     | 1    | 1   |
| Maths,Phy,Che           | 1     | 1    | 1   |
+-------------------------+-------+------+------+

我试图使用此答案（how to split a column into multiple columns in mysql）

中公布的子字符串

但我无法按照我想要的方式工作

Answer 1

可以使用类似值的结果

select marks
      , (marks like '%Maths%') as Maths
      , (marks like '%Phy%') as Phy
      , (marks like '%Che%') as Che
from my table

Answer 2

一种选择是使用MySQL FIND_IN_SET功能。如果返回0或NULL，则在集合中找不到该项。如果它返回非零，则表示该集合中项目的位置。我们可以测试函数的返回值，只返回零或一。

这样的事情：

  SELECT t.marks
       , IF(FIND_IN_SET( 'Maths'  ,t.marks),1,0) AS `Maths`
       , IF(FIND_IN_SET( 'Phy'    ,t.marks),1,0) AS `Phy`
       , IF(FIND_IN_SET( 'Che'    ,t.marks),1,0) AS `Che`
    FROM column_like_this t

分裂列为二进制矩阵

2 个答案: