1. 导入hellodb.sql生成数据库

# 本次在CentOS8.4操作系统及MySQL5.7.36上完成

mysql> select version();
+------------+
| version()  |
+------------+
| 5.7.36-log |
+------------+
1 row in set (0.00 sec)

[root@CentOS84 ]#mysql -uroot -ps*****2
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.7.36-log Source distribution

Copyright (c) 2000, 2021, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show tables;
ERROR 1046 (3D000): No database selected
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| mytestdb1          |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.06 sec)

mysql> quit

# 导入数据库并验证
[root@CentOS84 ]#mysql -uroot -ps*****2 < /data/hellodb_innodb.sql
mysql: [Warning] Using a password on the command line interface can be insecure.
[root@CentOS84 ]#mysql -uroot -ps*****2
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 10
Server version: 5.7.36-log Source distribution

Copyright (c) 2000, 2021, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hellodb            |
| mysql              |
| mytestdb1          |
| performance_schema |
| sys                |
+--------------------+
6 rows in set (0.00 sec)

1.1 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

# 进入hellodb数据库
mysql> use hellodb
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

#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 name,age from students where gender='M' and age>25;
+--------------+-----+
| 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 (0.02 sec)

1.2 以ClassID为分组依据，显示每组的平均年龄

mysql> 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 |
+---------+----------+
8 rows in set (0.02 sec)

1.3 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) from students group by classid having avg(age)>30;
+---------+----------+
| classid | avg(age) |
+---------+----------+
|    NULL |  63.5000 |
|       2 |  36.0000 |
|       5 |  46.0000 |
+---------+----------+
3 rows in set (0.01 sec)

1.4 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

# 创建用户
mysql> create user 'magedu'@'192.168.1.%' identified by 'centos'; 
Query OK, 0 rows affected (0.06 sec)

mysql> show grants for magedu@'192.168.1.%';
+----------------------------------------------+
| Grants for magedu@192.168.1.%                |
+----------------------------------------------+
| GRANT USAGE ON *.* TO 'magedu'@'192.168.1.%' |
+----------------------------------------------+
1 row in set (0.00 sec)

#授权
mysql> grant all on *.* to magedu@'192.168.1.%' identified by 'centos';
Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> show grants for magedu@'192.168.1.%';   
+-------------------------------------------------------+
| Grants for magedu@192.168.1.%                         |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'magedu'@'192.168.1.%' |
+-------------------------------------------------------+
1 row in set (0.00 sec)

mysql>

# 查询数据库内所有的账号
mysql> SELECT DISTINCT CONCAT('User: ''',user,'''@''',host,''';') AS query FROM mysql.user;
+------------------------------------+
| query                              |
+------------------------------------+
| User: 'shone'@'%';                 |
| User: 'magedu'@'192.168.1.%';      |
| User: 'summer'@'192.168.1.%';      |
| User: 'mysql.session'@'localhost'; |
| User: 'mysql.sys'@'localhost';     |
| User: 'root'@'localhost';          |
+------------------------------------+
6 rows in set (0.02 sec)