1、 导入hellodb.sql生成数据库 (1) 在students表中，查询年龄大于25岁，且为男性的同学的名字和年龄
mysql> select * from students;
+-------+---------------+-----+--------+---------+-----------+
| StuID | Name | Age | Gender | ClassID | TeacherID |
+-------+---------------+-----+--------+---------+-----------+
| 1 | Shi Zhongyu | 22 | M | 2 | 3 |
| 2 | Shi Potian | 22 | M | 1 | 7 |
| 3 | Xie Yanke | 53 | M | 2 | 16 |
| 4 | Ding Dian | 32 | M | 4 | 4 |
| 5 | Yu Yutong | 26 | M | 3 | 1 |
| 6 | Shi Qing | 46 | M | 5 | NULL |
| 7 | Xi Ren | 19 | F | 3 | NULL |
| 8 | Lin Daiyu | 17 | F | 7 | NULL |
| 9 | Ren Yingying | 20 | F | 6 | NULL |
| 10 | Yue Lingshan | 19 | F | 3 | NULL |
| 11 | Yuan Chengzhi | 23 | M | 6 | NULL |
| 12 | Wen Qingqing | 19 | F | 1 | NULL |
| 13 | Tian Boguang | 33 | M | 2 | NULL |
| 14 | Lu Wushuang | 17 | F | 3 | NULL |
| 15 | Duan Yu | 19 | M | 4 | NULL |
| 16 | Xu Zhu | 21 | M | 1 | NULL |
| 17 | Lin Chong | 25 | M | 4 | NULL |
| 18 | Hua Rong | 23 | M | 7 | NULL |
| 19 | Xue Baochai | 18 | F | 6 | NULL |
| 20 | Diao Chan | 19 | F | 7 | NULL |
| 21 | Huang Yueying | 22 | F | 6 | NULL |
| 22 | Xiao Qiao | 20 | F | 1 | NULL |
| 23 | Ma Chao | 23 | M | 4 | NULL |
| 24 | Xu Xian | 27 | M | NULL | NULL |
| 25 | Sun Dasheng | 100 | M | NULL | NULL |
+-------+---------------+-----+--------+---------+-----------+
25 rows in set (0.00 sec)
mysql> select name,age from students where age > 25 and Gender='m';
+--------------+-----+
| name | age |
+--------------+-----+
| Xie Yanke | 53 |
| Ding Dian | 32 |
| Yu Yutong | 26 |
| Shi Qing | 46 |
| Tian Boguang | 33 |
| Xu Xian | 27 |
| Sun Dasheng | 100 |
+--------------+-----+
7 rows in set (0.00 sec)
(2) 以ClassID为分组依据，显示每组的平均年龄
mysql> SELECT classid,AVG(age) FROM students WHERE classid IS NOT NULL GROUP BY classid;
+---------+----------+
| classid | AVG(age) |
+---------+----------+
| 2 | 36.0000 |
| 1 | 20.5000 |
| 4 | 24.7500 |
| 3 | 20.2500 |
| 5 | 46.0000 |
| 7 | 19.6667 |
| 6 | 20.7500 |
+---------+----------+
7 rows in set (0.00 sec)
(3) 显示第2题中平均年龄大于30的分组及平均年龄
mysql> select classid,AVG(age) as avgage from students where classid is not null group by classid having avgage > 30;
+---------+---------+
| classid | avgage |
+---------+---------+
| 2 | 36.0000 |
| 5 | 46.0000 |
+---------+---------+
2 rows in set (0.01 sec)
(4) 显示以L开头的名字的同学的信息
mysql> SELECT * FROM students WHERE NAME LIKE 'l%';
+-------+-------------+-----+--------+---------+-----------+
| StuID | Name | Age | Gender | ClassID | TeacherID |
+-------+-------------+-----+--------+---------+-----------+
| 8 | Lin Daiyu | 17 | F | 7 | NULL |
| 14 | Lu Wushuang | 17 | F | 3 | NULL |
| 17 | Lin Chong | 25 | M | 4 | NULL |
+-------+-------------+-----+--------+---------+-----------+
3 rows in set (0.00 sec)
2、数据库授权magedu用户，允许192.168.1.0/24网段可以连接mysql
mysql> create user 'magedu'@'192.168.1.%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
mysql> grant all privileges on `hellodb`.* to 'magedu'@'192.168.1.%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
