mysql查询男女平均年龄_mysql查询练习（三）

31、查询成绩比该课程平均成绩低的同学的成绩表

mysql> select * from score a where degree < (select avg(degree) from score b where o= o);

+-----+-------+--------+

| sno | cno | degree |

+-----+-------+--------+

| 101 | 3-106 | 70 |

| 103 | 3-105 | 59 |

| 104 | 3-107 | 48 |

| 105 | 3-105 | 82 |

| 106 | 3-108 | 10 |

| 107 | 3-106 | 68 |

+-----+-------+--------+

6 rows in set (0.00 sec)

32.查询所有任课教师的Tname和Depart

mysql> select tname,depart from teacher where tno in (select tno from course);

+-------+-----------+

| tname | depart |

+-------+-----------+

| b1 | computer |

| b2 | computer1 |

| b3 | computer1 |

| b4 | computer |

+-------+-----------+

4 rows