例如:查询所有学生的选课情况
Oracle写法:
SELECT s.SNAME, st.COURSE
FROM tt_student s,
(SELECT sc.SNO, wmsys.wm_concat(tc.CNAME) COURSE
FROM SC sc
INNER JOIN tt_course tc
ON tc.CNO = sc.CNO
GROUP BY sc.SNO) st
WHERE s.SNO = st.SNO
MySQL写法:
SELECT s.SNAME, st.COURSE
FROM tt_student s,
(SELECT sc.SNO, group_concat(tc.CNAME) COURSE
FROM SC sc
INNER JOIN tt_course tc
ON tc.CNO = sc.CNO
GROUP BY sc.SNO) st
WHERE s.SNO = st.SNO