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题目如下:
查询有课程成绩小于60分的同学的学号、姓名
首先咱们还是先分析题目,这道题要使用到两个表,score和student这两个表
score表中有本题需要的分数,student表中有咱们需要的学号和姓名,
首先就是要连接两表,我使用的是内连接
第一步:
select st.sid,st.sname,sc.student_id,sc.num from student st inner join score
sc on st.sid=sc.student_id
这样就得到了表sct(我给这个表起的别名)
然后去筛选就可以了,条件是有课程小于60
select sct.sid,sct.sname from (select st.sid,st.sname,sc.student_id,sc.num
from student st inner join score sc on st.sid=sc.student_id)sct where
sct.num<60;
这个表其实挺有意思的名字起得有意思,
而且结果是除了一个13学号的同学只学了一课没有低于60分其他的都低于60了哈哈。
今日分享到这啦~