MariaDB [hellodb]> create view view_stumessage as (select st.name,co.course,sc.score from students st inner join scores sc on st.stuid=sc.stuid inner join courses co on sc.courseid=co.courseid);
MariaDB [hellodb]> desc view_stumessage;
MariaDB [hellodb]>select * from view_stumessage;
MariaDB [hellodb]> show table status like 'view_stumessage'\G;
MariaDB [hellodb]> create view view_oldstudents as (select * from students where age>30);
MariaDB [hellodb]>select * from view_oldstudents;
+-------+--------------+-----+--------+---------+-----------+
| StuID | Name | Age | Gender | ClassID | TeacherID |
+-------+--------------+-----+--------+---------+-----------+
| 3 | Xie Yanke | 53 | M | 2 | 16 || 4 | Ding Dian | 32 | M | 4 | 4 || 6 | Shi Qing | 46 | M | 5 | NULL || 13 | Tian Boguang | 33 | M | 2 | NULL || 25 | Sun Dasheng | 100 | M | NULL | NULL |
+-------+--------------+-----+--------+---------+-----------+
//插入到了视图中，也插入到表中
MariaDB [hellodb]> insert into view_oldstudents(name,age)values('zhangsan',50);
//插入到了表中，插入视图中失败
MariaDB [hellodb]> insert into view_oldstudents(name,age)values('lisi',20);
MariaDB [hellodb]> drop view view_oldstudents;
自定义函数 UDF
MariaDB [hellodb]> create function simpleFun()returns varchar(20)return"Hello World!";
MariaDB [hellodb]>select simpleFun();
+--------------+
| simpleFun()|
+--------------+
| Hello World!|
+--------------+
MariaDB [hellodb]> show function status\G
MariaDB [hellodb]> show create function simpleFun\G
MariaDB [hellodb]>select * from mysql.proc\G //函数的存放位置
MariaDB [hellodb]> drop function simpleFun;
MariaDB [hellodb]> delimiter //
MariaDB [hellodb]> create function deleteById(uid smallint unsigned)returns varchar(20)
-> begin
-> delete from students where stuid = uid;
->return(select count(stuid) from students);
-> end //
Query OK, 0 rows affected (0.00 sec)
MariaDB [hellodb]> delimiter ;
MariaDB [hellodb]>select deleteByid(10);
+----------------+
| deleteByid(10)|
+----------------+
| 26 |
+----------------+
MariaDB [hellodb]> delimiter //
MariaDB [hellodb]> create function addTwoNumber(x smallint unsigned,y smallint unsigned)
-> returns smallint
-> begin
->declare a, b smallint unsigned; //定义局部变量
->set a = x, b = y; // 为变量赋值
->return a+b;
-> end //
Query OK, 0 rows affected (0.00 sec)
MariaDB [hellodb]> delimiter ;
MariaDB [hellodb]>select addTwoNumber(10,20);
+---------------------+
| addTwoNumber(10,20)|
+---------------------+
| 30 |
+---------------------+
MariaDB [hellodb]> delimiter //
MariaDB [hellodb]> create procedure deleteById(in uid smallint unsigned, out num smallint unsigned)
-> begin
-> delete from students where stuid >=uid;
->select row_count() into num;
-> end//
Query OK, 0 rows affected (0.00 sec)
MariaDB [hellodb]> delimiter ;
MariaDB [hellodb]> call deleteById(12,@Line);
Query OK, 1 row affected (0.01 sec)
MariaDB [hellodb]>select @Line;
+-------+
| @Line |
+-------+
| 16 |
+-------+
trigger 触发器
MariaDB [hellodb]> create table student_info(
-> stu_id int(11) not null auto_increment,
-> stu_name varchar(255) default null,
-> primary key(stu_id)
->);
MariaDB [hellodb]> create table student_count(
-> student_count int(11) default 0
->);
MariaDB [hellodb]> insert into student_count values(0);
MariaDB [hellodb]> create trigger trigger_student_count_insert
-> after insert
-> on student_info for each row
-> update student_count set student_count=student_count+1;
MariaDB [hellodb]> create trigger trigger_student_count_delete
-> after delete
-> on student_info for each row
-> update student_count set student_count=student_count-1;
MariaDB [hellodb]> insert into student_info values(1,'a');
Query OK, 1 row affected (0.00 sec)
MariaDB [hellodb]>select * from student_info;
+--------+----------+
| stu_id | stu_name |
+--------+----------+
| 1 | a |
+--------+----------+
1 row inset(0.00 sec)
MariaDB [hellodb]>select * from student_count;
+---------------+
| student_count |
+---------------+
| 1 |
+---------------+
MariaDB [hellodb]> show triggers\G
MariaDB [hellodb]>select * from information_schema.triggers\G
MariaDB [hellodb]> drop trigger trigger_student_count_insert;
MariaDB [hellodb]> drop trigger trigger_student_count_delete;
用户账号和权限管理
MariaDB [mysql]>select user,host,password from user;
+------+----------------+----------+
| user | host | password |
+------+----------------+----------+
| root | localhost ||| root | centos7-19.com ||| root | 127.0.0.1 ||| root | ::1 |||| localhost |||| centos7-19.com ||
+------+----------------+----------+
版本高的数据库密码存放在 mysql.user.authentication_string字段中
MariaDB [mysql]> create user test@'192.168.209.%' identified by 'centos';
-- 连接远程数据库主机
[root@Centos6-9 ~]# mysql -utest -pcentos -h 192.168.209.19 -P3306
MariaDB [mysql]>rename user test@'192.168.209.%' to alice@'192.168.209.%';//改名
MariaDB [mysql]> drop user ''@'centos7-19.com'; // 删除用户
MariaDB [mysql]>set password for'root'@'localhost'=password('centos'); //设置密码
[root@centos7-19 ~]# mysql -uroot -pcentos //默认以 root@localhost[root@centos7-19 ~]# mysql -uroot -p123 -h 127.0.0.1 //不能登陆到数据库，作反向解析了
ERROR 1045 (28000): Access denied for user 'root'@'localhost'(using password: YES)
skip_name_resolve 写入到配置文件中重启，[email protected] 就可以登陆了
MariaDB [mysql]> update user set password=password('123') where user='root' and host='centos7-19.com'; //修改密码
MariaDB [mysql]> flush privileges;
-- 忘记了数据库root的密码怎么办？
[root@centos7-19 ~]# vim /etc/my.cnf //修改，重启生效[mysqld]
skip-grant-tables
skip-networking
关闭了3306端口号，只能本地连接数据库，不用密码
然后修改mysql.user.password字段的值或重新设置密码
删除配置文件/etc/my.cnf以上两行，重新启动数据库
-- 创建用户并授权
MariaDB [hellodb]> grant all on hellodb.* to test@'192.168.209.29' identified by '123';
-- 查看权限
MariaDB [hellodb]> show grants for test@'192.168.209.29';
MariaDB [hellodb]> show grants for current_user();
-- 取消删除的权限
MariaDB [hellodb]> revoke delete on hellodb.* from test@'192.168.209.29';
MariaDB [hellodb]> revoke drop on hellodb.* from test@'192.168.209.29';
