建表语句点击详见
– 查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
SELECT
st
.s_id
,st
.s_name
,AVG(sc
.s_score
)
FROM student st
LEFT JOIN score sc
ON sc
.s_id
=st
.s_id
WHERE sc
.s_id
IN
(
SELECT
sc
.s_id
FROM score sc
WHERE sc
.s_score
<60 OR sc
.s_score
IS NULL
GROUP BY sc
.s_id
HAVING COUNT(1)>=2
)
GROUP BY st
.s_id
