mysql - 如何在 MySQL 中将字符串列读取为列表？

Question

我有一张 table 。它有两列 class_id和 student .列学生是学生列表。学生列的数据类型为 varchar .我想编写一个 SQL 查询来返回行，其中学生列是较大列表的子集，例如 ["A", "B", "C", "D", "E", "F", "G"]

class_id      student
1             ["A","B"]
2             ["G","K","E"]
3             ["A","B","I"]

对于上面的例子，我的查询应该只返回一行 class_id 1 .
这是我到目前为止所拥有的

select * from A where student in ("A", "B", "C", "D", "E", "F", "G")

但它不起作用。

Answer 1

这并没有回答你的问题，但它确实显示了应该如何做到这一点。将您的数据写为:

class    student
 1        A
 1        B
 2        G
 2        K
 2        E
 3        A
 3        B
 3        I

现在，您可以回答诸如“A 正在参加哪些类(class)？”之类的问题。

SELECT UNIQUEROW class FROM A WHERE student='A'

和“A 和 B 一起上哪些类(class)？”

SELECT class, COUNT(*) AS count FROM A WHERE student IN ('A','B') GROUP BY class HAVING count = 2;