SQL语句高级（十）——子查询

一、子查询
查询和“C”同学同性别的所有同学的sname：
mysql> select ssex from student where sname='C';
+-------+
| ssex  |
+-------+
| woman |
+-------+
1 row in set (0.01 sec)

mysql> select sname,ssex from student 
	-> where ssex=(select ssex from student where sname='C');
+-------+-------+
| sname | ssex  |
+-------+-------+
| C     | woman |
| C++   | woman |
| C#    | woman |
| JS    | woman |
+-------+-------+
4 rows in set (0.00 sec)

二、子查询
查询和“C”同学同性别并同班的所有同学的sname：
mysql> select sname,ssex,class from student 
	-> where ssex=(select ssex from student where sname='C')
    -> and class=(select class from student where sname='C');
+-------+-------+-------+
| sname | ssex  | class |
+-------+-------+-------+
| C     | woman | 95034 |
| C#    | woman | 95034 |
+-------+-------+-------+

三、子查询
查询所有选修csdaolun课程的男同学的成绩表：
mysql> select * from student where ssex = 'man';
+-----+--------+---------------------+-------+------+
| sno | sname  | sbirthday           | class | ssex |
+-----+--------+---------------------+-------+------+
| 100 | Java   | 1977-09-01 00:00:00 | 95033 | man  |
| 104 | Python | 1977-10-11 00:00:00 | 95033 | man  |
+-----+--------+---------------------+-------+------+
2 rows in set (0.00 sec)

mysql> select * from course where cname='csdaolun';
+-------+----------+-----+
| cno   | cname    | tno |
+-------+----------+-----+
| 3-105 | csdaolun | 825 |
+-------+----------+-----+
1 row in set (0.00 sec)

mysql> select * from score 
	-> where cno=(select cno from course where cname='csdaolun')
    -> and sno in (select sno from student where ssex = 'man');
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 100 | 3-105 |     75 |
| 104 | 3-105 |     59 |
+-----+-------+--------+