Question

我在mysql中有以下表格

table payment_enum(
id int PK,
name text,
category_id int FK to category
)

table category(
id int PK,
category_name text
)

我想要的是：在payment_enum中，它有两个具有不同名称但具有相同category_id的列例如：

select * from payment_enum 
pk   name  category_id
1    'first'  2
2    'second' 2

PK = 2的类别名称为“笔记本电脑” 是否可以使用将产生以下结果的查询

category_name category_PK enum_names
laptops        2            first,second

伪查询

select c.name,c.pk, e.name as (concat (e.name,concat(',',select e2.name where e2.name like e.name from payment_enum as e2)))
 from category as c and payment_enum as e

Answer 1

您需要group_concat而不是concat

select c.name,group_concat(e.name) as enum_names
from category as c
left join payment_enum as e on c.id = e.category_id
group by c.name

Answer 2

试试这个：

select c.name as category_name ,c.pk as category_PK , GROUP_CONCAT(p.name) as enum_names from
(select * from category) as c
left JOIN
(select * from payment_enum) as p
on c.id = p.category_id GROUP BY  c.name,c.pk

Concat两个字符串具有相同的FK

2 个答案: