1、 导入hellodb.sql生成数据库
[root@centos7 ~]# mysql < hellodb_innodb.sql
(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
MariaDB [hellodb]> select * from students where Age >25 and Gender='M';
+-------+--------------+-----+--------+---------+-----------+
| StuID | Name | Age | Gender | ClassID | TeacherID |
+-------+--------------+-----+--------+---------+-----------+
| 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 |
| 13 | Tian Boguang | 33 | M | 2 | NULL |
| 24 | Xu Xian | 27 | M | NULL | NULL |
| 25 | Sun Dasheng | 100 | M | NULL | NULL |
+-------+--------------+-----+--------+---------+-----------+
(2) 以ClassID为分组依据，显示每组的平均年龄
MariaDB [hellodb]> select ClassID,avg(Age) from students group by ClassID;
+---------+----------+
| ClassID | avg(Age) |
+---------+----------+
| NULL | 63.5000 |
| 1 | 20.5000 |
| 2 | 36.0000 |
| 3 | 20.2500 |
| 4 | 24.7500 |
| 5 | 46.0000 |
| 6 | 20.7500 |
| 7 | 19.6667 |
+---------+----------+
(3) 显示第2题中平均年龄大于30的分组及平均年龄
MariaDB [hellodb]> select ClassID,avg(Age) from students group by ClassID having avg(Age) >30;
+---------+----------+
| ClassID | avg(Age) |
+---------+----------+
| NULL | 63.5000 |
| 2 | 36.0000 |
| 5 | 46.0000 |
+---------+----------+
(4) 显示以L开头的名字的同学的信息
MariaDB [hellodb]> 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 |
+-------+-------------+-----+--------+---------+-----------+
2、数据库授权magedu用户，允许192.168.1.0/24网段可以连接mysql
MariaDB [mysql]> create user magedu@'192.168.1.%' IDENTIFIED BY '123456';
MariaDB [(none)]> SHOW GRANTS FOR magedu@'192.168.1.%';
+-----------------------------------------------------------------------------------------------------------------+
| Grants for magedu@192.168.1.% |
+-----------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'magedu'@'192.168.1.%' IDENTIFIED BY PASSWORD '*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9' |
+-----------------------------------------------------------------------------------------------------------------+
