mysql里面的count函數連表查詢某個字段在另一張表的數量
2022-05-29 22:33:48

select c.*,
(select count(hcus.id) from  hcus where c.id=hcus.id and study_status='finished') as learnStuNum,
(select count(hcus.id) from  hcus where c.id=id ) as learnNum
from  c
where c.id=#{id}