我有下面的查询,该查询应该有效 . 但是,MySQL给了我错误消息'Subquery返回多行' .
select e.episode_pk,
(select group_concat(d.fulldescription separator ', ')
from episode_rhythm er join diagnosis d on er.diagnosis_fk = d.diagnosis_pk
WHERE er.episode_fk = e.episode_pk group by d.fulldescription) as rhythmDesc
from episode e
WHERE e.patientid_fk='89976'
在此查询中使用group_concat的全部目的是每个'episode'只返回一行 .
外部选择返回多行 .
内部选择,当运行单个剧集表主键时,返回单行,如您所怀疑:
select group_concat(d.fulldescription separator ', ')
from episode_rhythm er join diagnosis d on er.diagnosis_fk = d.diagnosis_pk
WHERE er.episode_fk = 234776 group by d.fulldescription
没有group_concat的内部选择,当运行单个剧集表主键时,可能会返回多行:
select d.fulldescription
from episode_rhythm er join diagnosis d on er.diagnosis_fk = d.diagnosis_pk
WHERE er.episode_fk = 234776
如我所料,我需要做些什么才能让它发挥作用?
1 回答
SELECT中的子查询有点令人怀疑 .
我猜你要找的是: