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
(2) 以ClassID为分组依据，显示每组的平均年龄
(3) 显示第2题中平均年龄大于30的分组及平均年龄
(4) 显示以L开头的名字的同学的信息
1、导入hellodb.sql生成数据库
[root@centos7 ~]# mysql -uroot -pliucan123 <hellodb_innodb.sql
mysql: [Warning] Using a password on the command line interface can be insecure.
[root@centos7 ~]# mysql -uroot -pliucan123
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 4
Server version: 5.7.32 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
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 |
| log |
| mysql |
| performance_schema |
| pid |
| sys |
+--------------------+
7 rows in set (0.00 sec)
（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> use hellodb
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 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 (0.00 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) 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 (0.00 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 |
+-------+-------------+-----+--------+---------+-----------+
2、数据库授权magedu用户，允许192.168.1.0/24网段可以连接mysql
mysql> grant all on *.* to 'magedu'@'192.168.1.%' identified by 'magedu2020' with grant option
mysql> show grants for 'magedu'@'192.168.1.%';
+-------------------------------------------------------------------------+
| Grants for magedu@192.168.1.% |
+-------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'magedu'@'192.168.1.%' WITH GRANT OPTION |
+-------------------------------------------------------------------------+
1 row in set (0.00 sec)
