MariaDB [hellodb]> source /root/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 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 (0.001 sec)
(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 |
+---------+----------+
8 rows in set (0.001 sec)
(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) as 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 (0.000 sec)
(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 |
+-------+-------------+-----+--------+---------+-----------+
3 rows in set (0.000 sec)
2、数据库授权magedu用户，允许192.168.1.0/24网段可以连接mysql
MariaDB [hellodb]> create user 'magedu'@'192.168.1.%' ;
Query OK, 0 rows affected (0.011 sec)
MariaDB [hellodb]> grant all privileges on hellodb.* to 'magedu'@'192.168.1.%' ;
Query OK, 0 rows affected (0.001 sec)
因没有设置密码，连接时空密码
[root@localhost ~]# mysql -umagedu -p
Enter password:
Welcome to the MariaDB monitor. Commands end with ; or g.
Your MariaDB connection id is 18
Server version: 10.4.21-MariaDB MariaDB Server
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