mysql一對(duì)多查詢問(wèn)題

A表stu_id 應(yīng)該為唯一索引或主鍵，結(jié)果不存在重復(fù)的情況。即使學(xué)生名字重復(fù)也應(yīng)該顯示。

SELECT A.stu_id,A.name FROM A JOIN B ON A.stu_id = B.stu_id JOIN C ON C.stu_id = A.stu_id

join+group by即可,興趣表和特長(zhǎng)表加上stu_id的索引.

from t_student s 
join t_its i on i.stu_id=s.stu_id 
join t_gda g on g.stu_id=s.stu_id
group by s.stu_id

SELECT stu_id, name FROM A WHERE stu_id in 
(
    SELECT stu_id FROM B
) AND stu_id in
(
    SELECT stu_id FROM C
)
GROUP BY name