select简单循环嵌套

访问学生的物理最高成绩，并且打印出来，单个要打印出所有的信息 在添加几个 and 就可以啦。

select  student.gender,student.sname from student where

student.sid =( select sid from s_mark where s_mark.score= (select max(score) from s_mark   where s_mark.cid =(select cid from course where cname='physics' ))

and    s_mark.cid = (select cid from course where cname='physics'));

步骤：

1、先通过course表得到物理的cid

select cid from course where cname='physics'

2、用得到的cid确定s_mark表中的最高成绩

s_mark.score  =  (   select     max(score)    from s_mark     where s_mark.cid =(select cid from course where cname='physics' )

3、通过最高成绩和cid确定唯一的sid

上面这个一长串

-----+-----+-----+-------+
| mid | sid | cid | score |  //表;s_mark
+-----+-----+-----+-------+
|   1 |   1 |   1 |    80 |
|   2 |   2 |   1 |    85 |
|   3 |   3 |   1 |    90 |
|   4 |   1 |   2 |    60 |
|   5 |   2 |   2 |    90 |
|   6 |   3 |   3 |    75 |
|   7 |   1 |   3 |    95 |
|   8 |   2 |   3 |    75 |
|   9 |   3 |   3 |    85 |
+-----+-----+-----+-------+
-----+-------+--------+
| sid | sname | gender | //表;student
+-----+-------+--------+
|   1 | Tom   | male   |
|   2 | Jack  | male   |
|   3 | Rose  | female |
+-----+-------+--------+
+-----+-----------+
| cid | cname     |//表；course
+-----+-----------+
|   1 | math      |
|   2 | physics   |
|   3 | chemistry |
+-----+-----------+

总结：都是围绕着最基本的格式，

select * from course,stduent,s_mark  where(…….)  and (………);