mysql - 将 SQL 结果与逗号分隔符结合起来

Question

我需要组合以下查询中的标签，并用逗号分隔符分隔:

SQL

select question.text,tag.text
from question
left join q_t on question.id = q_t.wall_id
left join tag on q_t.tag_id = tag.id
where question.id in (1000001,1000002,1000003,1000004,1000005) 
order by field(question.id,1000001,1000002,1000003,1000004,1000005)

当前结果:

text                         text
where is England?         Geography
where is England?         Continent
where is England?         general_knowledge
how many ...?             sport
how many ...?             Europe

请求的结果:

text                         text
where is England?         Geography,Continent,general_knowledge
how many ...?             sport,Europe

谢谢

Answer 1

您可以使用group_concat但从结果连接有 1024 个字符的默认限制，剩余数据将被截断，但是可以通过以下手册增加此限制，但它也依赖于 max_allowed_packet也是

select question.text,group_concat(tag.text)
from question
left join q_t on question.id = q_t.wall_id
left join tag on q_t.tag_id = tag.id
where question.id in (1000001,1000002,1000003,1000004,1000005) 
group by  question.text
order by field(question.id,1000001,1000002,1000003,1000004,1000005)