第14周

1.导入hellodb.sql生成数据库

导入hellodb数据库：
[root@centosmin7 ~]# mysql -p < hellodb_innodb.sql 
[root@centosmin7 ~]# mysql -p 
MariaDB [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| hellodb            |
| information_schema |
| mysql              |
| performance_schema |
+--------------------+
4 rows in set (0.01 sec)
MariaDB [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| hellodb            |
| information_schema |
| mysql              |
| performance_schema |
+--------------------+
4 rows in set (0.01 sec)

MariaDB [(none)]> use hellodb;
Database changed
MariaDB [hellodb]> show tables;
+-------------------+
| Tables_in_hellodb |
+-------------------+
| classes           |
| coc               |
| courses           |
| scores            |
| students          |
| teachers          |
| toc               |
+-------------------+
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

MariaDB [hellodb]> desc students;
+-----------+---------------------+------+-----+---------+----------------+
| Field     | Type                | Null | Key | Default | Extra          |
+-----------+---------------------+------+-----+---------+----------------+
| StuID     | int(10) unsigned    | NO   | PRI | NULL    | auto_increment |
| Name      | varchar(50)         | NO   |     | NULL    |                |
| Age       | tinyint(3) unsigned | NO   |     | NULL    |                |
| Gender    | enum('F','M')       | NO   |     | NULL    |                |
| ClassID   | tinyint(3) unsigned | YES  |     | NULL    |                |
| TeacherID | int(10) unsigned    | YES  |     | NULL    |                |
+-----------+---------------------+------+-----+---------+----------------+
6 rows in set (0.01 sec)

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 (0.00 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 (0.00 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 age FROM students GROUP BY ClassID HAVING age > 30;
+---------+---------+
| ClassID | 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

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 (0.00 sec)

2.数据库授权magedu用户，允许192.168.177.0/24网段可以连接mysql

MariaDB [(none)]> use hellodb
Database changed
MariaDB [hellodb]> CREATE user magedu@'192.168.177.%' identified by 'stone';
Query OK, 0 rows affected (0.00 sec)

MariaDB [hellodb]> SELECT user,host,password FROM mysql.user WHERE user='magedu';
+--------+---------------+-------------------------------------------+
| user   | host          | password                                  |
+--------+---------------+-------------------------------------------+
| magedu | 192.168.177.% | *BBE37FCE8F92DCEABE3FFE8C290F7A15F12F9DCF |
+--------+---------------+-------------------------------------------+
1 row in set (0.00 sec)


MariaDB [hellodb]> GRANT all on *.* to magedu@'192.168.177.%' identified by 'stone';
Query OK, 0 rows affected (0.00 sec)
MariaDB [hellodb]> SHOW GRANTS FOR magedu@'192.168.177.%';
+----------------------------------------------------------------------------------------------------------------------------+
| Grants for magedu@192.168.177.%                                                                                            |
+----------------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'magedu'@'192.168.177.%' IDENTIFIED BY PASSWORD '*BBE37FCE8F92DCEABE3FFE8C290F7A15F12F9DCF' |
+----------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

修改账户权限：
MariaDB [hellodb]> use mysql
Database changed
MariaDB [mysql]> UPDATE user set host='192.168.177.%' WHERE user='magedu';
Query OK, 0 rows affected (0.00 sec)
Rows matched: 1  Changed: 0  Warnings: 0

MariaDB [mysql]> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)

MariaDB [mysql]> SELECT user,host,password FROM user WHERE user='magedu';
+--------+---------------+-------------------------------------------+
| user   | host          | password                                  |
+--------+---------------+-------------------------------------------+
| magedu | 192.168.177.% | *BBE37FCE8F92DCEABE3FFE8C290F7A15F12F9DCF |
+--------+---------------+-------------------------------------------+
1 row in set (0.00 sec)

3.总结mysql常见的存储引擎以及特点。
https://www.jianshu.com/p/cf4e34fb999f