mysql基础
1. 关系型数据库介绍
1.1 数据结构模型
数据结构模型主要有:
- 层次模型
- 网状结构
- 关系模型
关系模型:
二维关系:row,column
数据库管理系统:DBMS
关系:Relational,RDBMS
1.2 RDBMS专业名词
常见的关系型数据库管理系统:
- MySQL:MySQL,MariaDB,Percona-Server
- PostgreSQL:简称为pgsql
- Oracle
- MSSQL
SQL:Structure Query Language,结构化查询语言
约束:constraint,向数据表提供的数据要遵守的限制
- 主键约束:一个或多个字段的组合,填入的数据必须能在本表中唯一标识本行。且必须提供数据,不能为空(NOT NULL)。
一个表只能存在一个
- 惟一键约束:一个或多个字段的组合,填入的数据必须能在本表中唯一标识本行。允许为空(NULL)
一个表可以存在多个
- 外键约束:一个表中的某字段可填入数据取决于另一个表的主键已有的数据
- 检查性约束
索引:将表中的一个或多个字段中的数据复制一份另存,并且这些数据需要按特定次序排序存储
1.3 关系型数据库的常见组件
关系型数据库的常见组件有:
- 数据库:database
- 表:table,由行(row)和列(column)组成
- 索引:index
- 视图:view
- 用户:user
- 权限:privilege
- 存储过程:procedure
- 存储函数:function
- 触发器:trigger
- 事件调度器:event scheduler
1.4 SQL语句
SQL语句有三种类型:
- DDL:Data Defination Language,数据定义语言
- DML:Data Manipulation Language,数据操纵语言
- DCL:Data Control Language,数据控制语言
2. mysql安装与配置
2.1 mysql安装
mysql安装方式有三种:
- 源代码:编译安装
- 二进制格式的程序包:展开至特定路径,并经过简单配置后即可使用
- 程序包管理器管理的程序包:
rpm:有两种
- OS Vendor:操作系统发行商提供的
- 项目官方提供的
deb
#配置mysql的yum源
wget -O /usr/src/mysql57-community-release-el7-10.noarch.rpm \
http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
rpm -Uvh /usr/src/mysql57-community-release-el7-10.noarch.rpm
#安装mysql5.7
yum -y install mysql-community-server mysql-community-client \
mysql-community-common mysql-community-devel
2.2 mysql配置
#启动mysql并设置开机自动启动
systemctl enable --now mysqld
systemctl status mysqld
#确保3306端口已经监听起来
ss -antl
#在日志文件中找出临时密码
grep "password" /var/log/mysqld.log
#使用获取到的临时密码登录mysql
[root@localhost ~]# mysql -uroot -p
Enter password: //此处输入密码,可以直接复制你的密码粘贴至此处,也可手动输入
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.23
Copyright (c) 2000, 2018, 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> //看到有这样的标识符则表示成功登录了
//修改mysql登录密码
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password_length=1;
Query OK, 0 rows affected (0.01 sec)
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'wangqing123!';
Query OK, 0 rows affected (0.00 sec)
mysql> quit
Bye
//为避免mysql自动升级,这里需要卸载最开始安装的yum源
rpm -e mysql57-community-release
3. mysql的程序组成
客户端
mysql:CLI交互式客户端程序
mysql_secure_installation:安全初始化,强烈建议安装完以后执行此命令
mysqldump:mysql备份工具
mysqladmin服务器端
mysqld
3.1 mysql工具使用
//语法:mysql [OPTIONS] [database]
//常用的OPTIONS:
-uUSERNAME //指定用户名,默认为root
-hHOST //指定服务器主机,默认为localhost,推荐使用ip地址
-pPASSWORD //指定用户的密码
-P# //指定数据库监听的端口,这里的#需用实际的端口号代替,如-P3307
-V //查看当前使用的mysql版本
-e //不登录mysql执行sql语句后退出,常用于脚本
[root@localhost ~]# mysql -V
mysql Ver 14.14 Distrib 5.7.23, for Linux (x86_64) using EditLine wrapper
[root@localhost ~]# mysql -uroot -pwangqing123! -h127.0.0.1
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: 5.7.23 MySQL Community Server (GPL)
Copyright (c) 2000, 2018, 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>
//注意,不推荐直接在命令行里直接用-pPASSWORD的方式登录,而是使用-p选项,然后交互式输入密码
[root@localhost ~]# mysql -uroot -p -h127.0.0.1
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.7.23 MySQL Community Server (GPL)
Copyright (c) 2000, 2018, 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>
[root@localhost ~]# mysql -uroot -p -h 127.0.0.1 -e 'SHOW DATABASES;'
Enter password:
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| wangqingge |
+--------------------+
3.2 服务器监听的两种socket地址
4. mysql数据库操作
4.1 DDL操作
4.1.1 数据库操作
//创建数据库
//语法:CREATE DATABASE [IF NOT EXISTS] 'DB_NAME';
//创建数据库wangqingge
mysql> CREATE DATABASE IF NOT EXISTS wangqingge;
Query OK, 1 row affected (0.00 sec)
//查看当前实例有哪些数据库
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| wangqingge |
+--------------------+
5 rows in set (0.00 sec)
//删除数据库
//语法:DROP DATABASE [IF EXISTS] 'DB_NAME';
//删除数据库wangqingge
mysql> DROP DATABASE IF EXISTS wangqingge;
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
4.1.2 表操作
//创建表
//语法:CREATE TABLE table_name (col1 datatype 修饰符,col2 datatype 修饰符) ENGINE='存储引擎类型';
//在数据库wangqingge里创建表wangqing
mysql> CREATE DATABASE wangqingge; //创建数据库wangqingge
Query OK, 1 row affected (0.00 sec)
mysql> use wangqingge; //进入wangqingge数据库
Database changed
mysql> CREATE TABLE wangqing (id int NOT NULL,name VARCHAR(100) NOT NULL,age tinyint); //创建wangqing表
Query OK, 0 rows affected (0.09 sec)
//查看当前数据库有哪些表
mysql> SHOW TABLES;
+----------------------+
| Tables_in_wangqingge |
+----------------------+
| wangqing |
+----------------------+
1 row in set (0.00 sec)
//删除表
//语法:DROP TABLE [ IF EXISTS ] 'table_name';
//删除表wangqing
mysql> DROP TABLE wangqing;
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW TABLES;
Empty set (0.00 sec)
4.1.3 用户操作
mysql用户帐号由两部分组成,如'USERNAME'@'HOST',表示此USERNAME只能从此HOST上远程登录
这里('USERNAME'@'HOST')的HOST用于限制此用户可通过哪些主机远程连接mysql程序,其值可为:
- IP地址,如:172.16.12.129
- 通配符
> %:匹配任意长度的任意字符,常用于设置允许从任何主机登录
> _:匹配任意单个字符
//数据库用户创建
//语法:CREATE USER 'username'@'host' [IDENTIFIED BY 'password'];
//创建数据库用户wangqing
mysql> CREATE USER 'wangqing'@'127.0.0.1' IDENTIFIED BY 'wangqing123!';
Query OK, 0 rows affected (0.00 sec)
//使用新创建的用户和密码登录
[root@localhost ~]# mysql -uwangqing -pwangqing123! -h127.0.0.1
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 6
Server version: 5.7.23 MySQL Community Server (GPL)
Copyright (c) 2000, 2018, 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>
//删除数据库用户
//语法:DROP USER 'username'@'host';
mysql> DROP USER 'wangqing'@'127.0.0.1';
Query OK, 0 rows affected (0.00 sec)
4.1.4 查看命令SHOW
mysql> SHOW CHARACTER SET; //查看支持的所有字符集
+----------+---------------------------------+---------------------+--------+
| Charset | Description | Default collation | Maxlen |
+----------+---------------------------------+---------------------+--------+
| big5 | Big5 Traditional Chinese | big5_chinese_ci | 2 |
| dec8 | DEC West European | dec8_swedish_ci | 1 |
| cp850 | DOS West European | cp850_general_ci | 1 |
| hp8 | HP West European | hp8_english_ci | 1 |
| koi8r | KOI8-R Relcom Russian | koi8r_general_ci | 1 |
| latin1 | cp1252 West European | latin1_swedish_ci | 1 |
......
......
mysql> SHOW ENGINES; //查看当前数据库支持的所有存储引擎
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine | Support | Comment
| Transactions | XA | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| InnoDB | DEFAULT | Supports transactions, row-level locking, and
foreign keys | YES | YES | YES |
| MRG_MYISAM | YES | Collection of identical MyISAM tables
| NO | NO | NO |
| MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO |
| BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO |
| MyISAM | YES | MyISAM storage engine | NO | NO | NO |
| CSV | YES | CSV storage engine | NO | NO | NO |
| ARCHIVE | YES | Archive storage engine | NO | NO | NO |
| PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO |
| FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
9 rows in set (0.00 sec)
mysql> SHOW DATABASES; //查看数据库信息
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| wangqingge |
+--------------------+
5 rows in set (0.00 sec)
mysql> SHOW TABLES FROM wangqingge; //不进入某数据库而列出其包含的所有表
+----------------------+
| Tables_in_wangqingge |
+----------------------+
| wangqing |
+----------------------+
1 row in set (0.00 sec)
//查看表结构
//语法:DESC [db_name.]table_name;
mysql> DESC wangqingge.wangqing;
+-------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id | int(11) | NO | | NULL | |
| name | varchar(100) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.03 sec)
//查看某表的创建命令
//语法:SHOW CREATE TABLE table_name;
mysql> SHOW CREATE TABLE wangqingge.wangqing;
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| wangqing | CREATE TABLE `wangqing` (
`id` int(11) NOT NULL,
`name` varchar(100) NOT NULL,
`age` tinyint(4) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
//查看某表的状态
//语法:SHOW TABLE STATUS LIKE 'table_name'\G
mysql> use wangqingge; //进入数据库wangqingge
Database changed
mysql> SHOW TABLE STATUS LIKE 'wangqing'\G //查看wangqing表的状态
*************************** 1. row ***************************
Name: wangqing
Engine: InnoDB
Version: 10
Row_format: Dynamic
Rows: 0
Avg_row_length: 0
Data_length: 16384
Max_data_length: 0
Index_length: 0
Data_free: 0
Auto_increment: NULL
Create_time: 2018-08-13 00:53:21
Update_time: NULL
Check_time: NULL
Collation: latin1_swedish_ci
Checksum: NULL
Create_options:
Comment:
1 row in set (0.00 sec)
4.1.5 获取帮助
//获取命令使用帮助
//语法:HELP keyword;
mysql> HELP CREATE TABLE; //获取创建表的帮助
Name: 'CREATE TABLE'
Description:
Syntax:
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
(create_definition,...)
[table_options]
[partition_options]
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
[(create_definition,...)]
[table_options]
[partition_options]
[IGNORE | REPLACE]
[AS] query_expression
......
......
4.2 DML操作
DML操作包括增(INSERT)、删(DELETE)、改(UPDATE)、查(SELECT),均属针对表的操作。
4.2.1 INSERT语句
//DML操作之增操作insert
//语法:INSERT [INTO] table_name [(column_name,...)] {VALUES | VALUE} (value1,...),(...),...
mysql> use wangqingge;
Database changed
mysql> INSERT INTO wangqing (id,name,age) VALUE (1,'tom',20); //一次插入一条记录
Query OK, 1 row affected (0.01 sec)
mysql> INSERT INTO wangqing (id,name,age) VALUES (2,'jerry',23),(3,'wangqing',25),(4,'sean',28),(5,'zhangshan',26),(6,'zhangshan',20),(7,'lisi',NULL); //一次插入多条记录
Query OK, 4 rows affected (0.01 sec)
Records: 4 Duplicates: 0 Warnings: 0
4.2.2 SELECT语句
字段column表示法
条件判断语句WHERE
ORDER BY:排序,默认为升序(ASC)
//DML操作之查操作select
//语法:SELECT column1,column2,... FROM table_name [WHERE clause] [ORDER BY 'column_name' [DESC]] [LIMIT [m,]n];
mysql> use wangqingge;
Database changed
mysql> select * from wangqing;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT name FROM wangqing;
+-----------+
| name |
+-----------+
| tom |
| jerry |
| wangqing |
| sean |
| zhangshan |
| zhangshan |
| lisi |
+-----------+
7 rows in set (0.01 sec)
mysql> SELECT * FROM wangqing ORDER BY age;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 7 | lisi | NULL |
| 1 | tom | 20 |
| 6 | zhangshan | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 5 | zhangshan | 26 |
| 4 | sean | 28 |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT * FROM wangqing ORDER BY age DESC;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 3 | wangqing | 25 |
| 2 | jerry | 23 |
| 1 | tom | 20 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT * FROM wangqing ORDER BY age limit 2;
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | NULL |
| 1 | tom | 20 |
+----+------+------+
2 rows in set (0.00 sec)
mysql> SELECT * FROM wangqing ORDER BY age limit 1,2;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 6 | zhangshan | 20 |
+----+-----------+------+
2 rows in set (0.00 sec)
mysql> SELECT * FROM wangqing WHERE age >= 25;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
+----+-----------+------+
3 rows in set (0.00 sec)
mysql> SELECT * FROM wangqing WHERE age >= 25 AND name = 'zhangshan';
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 5 | zhangshan | 26 |
+----+-----------+------+
1 row in set (0.00 sec)
mysql> SELECT * FROM wangqing WHERE age BETWEEN 23 and 28;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
+----+-----------+------+
4 rows in set (0.00 sec)
mysql> select * from wangqing where age is not null;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
+----+-----------+------+
6 rows in set (0.00 sec)
mysql> select * from wangqing where age is null;
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | NULL |
+----+------+------+
1 row in set (0.00 sec)
4.2.3 update语句
//DML操作之改操作update
//语法:UPDATE table_name SET column1 = new_value1[,column2 = new_value2,...] [WHERE clause] [ORDER BY 'column_name' [DESC]] [LIMIT [m,]n];
mysql> select * from wangqing;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> update wangqing set age = 30 where name = 'lisi';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from wangqing where name = 'lisi';
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | 30 |
+----+------+------+
1 row in set (0.00 sec)
4.2.4 delete语句
//DML操作之删操作delete
//语法:DELETE FROM table_name [WHERE clause] [ORDER BY 'column_name' [DESC]] [LIMIT [m,]n];
mysql> select * from wangqing;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | 30 |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> delete from wangqing where id = 7; //删除某条记录
Query OK, 1 row affected (0.00 sec)
mysql> select * from wangqing;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
+----+-----------+------+
6 rows in set (0.00 sec)
mysql> delete from wangqing; //删除整张表的内容
Query OK, 6 rows affected (0.00 sec)
mysql> select * from wangqing;
Empty set (0.00 sec)
mysql> desc wangqing;
+-------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id | int(11) | NO | | NULL | |
| name | varchar(100) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
4.2.5 truncate语句
truncate与delete的区别:
//语法:TRUNCATE table_name;
mysql> select * from wangqing;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> truncate wangqing;
Query OK, 0 rows affected (0.01 sec)
mysql> select * from wangqing;
Empty set (0.00 sec)
mysql> desc wangqing;
+-------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id | int(11) | NO | | NULL | |
| name | varchar(100) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
4.3 DCL操作
4.3.1 创建授权grant
权限类型(priv_type)
指定要操作的对象db_name.table_name
WITH GRANT OPTION:被授权的用户可将自己的权限副本转赠给其他用户,说白点就是将自己的权限完全复制给另一个用户。不建议使用。
GRANT priv_type,... ON [object_type] db_name.table_name TO ‘username'@'host' [IDENTIFIED BY 'password'] [WITH GRANT OPTION];
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| wangqingge |
+--------------------+
5 rows in set (0.00 sec)
//授权wangqing用户在数据库本机上登录访问所有数据库
mysql> GRANT ALL ON *.* TO 'wangqing'@'localhost' IDENTIFIED BY 'wangqing123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> GRANT ALL ON *.* TO 'wangqing'@'127.0.0.1' IDENTIFIED BY 'wangqing123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//授权wangqing用户在172.16.12.129上远程登录访问wangqingge数据库
mysql> GRANT ALL ON wangqingge.* TO 'wangqing'@'172.16.12.129' IDENTIFIED BY 'wangqing123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//授权wangqing用户在所有位置上远程登录访问wangqingge数据库
mysql> GRANT ALL ON *.* TO 'wangqing'@'%' IDENTIFIED BY 'wangqing123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)
4.3.2 查看授权
//查看当前登录用户的授权信息
mysql> SHOW GRANTS;
+---------------------------------------------------------------------+
| Grants for root@localhost |
+---------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION |
+---------------------------------------------------------------------+
2 rows in set (0.00 sec)
//查看指定用户wangqing的授权信息
mysql> SHOW GRANTS FOR wangqing;
+-----------------------------------------------+
| Grants for wangqing@% |
+-----------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'wangqing'@'%' |
+-----------------------------------------------+
1 row in set (0.00 sec)
mysql> SHOW GRANTS FOR 'wangqing'@'localhost';
+-------------------------------------------------------+
| Grants for wangqing@localhost |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'wangqing'@'localhost' |
+-------------------------------------------------------+
1 row in set (0.00 sec)
mysql> SHOW GRANTS FOR 'wangqing'@'127.0.0.1';
+-------------------------------------------------------+
| Grants for wangqing@127.0.0.1 |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'wangqing'@'127.0.0.1' |
+-------------------------------------------------------+
1 row in set (0.00 sec)
4.3.3 取消授权REVOKE
//语法:REVOKE priv_type,... ON db_name.table_name FROM 'username'@'host';
mysql> REVOKE ALL ON *.* FROM 'wangqing'@'172.16.12.129';
Query OK, 0 rows affected (0.00 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
注意:mysql服务进程启动时会读取mysql库中的所有授权表至内存中:
- GRANT或REVOKE等执行权限操作会保存于表中,mysql的服务进程会自动重读授权表,并更新至内存中
- 对于不能够或不能及时重读授权表的命令,可手动让mysql的服务进程重读授权表
mysql> FLUSH PRIVILEGES;
作业
1.搭建mysql服务
2.创建一个以你名字为名的数据库,并创建一张表student,该表包含三个字段(id,name,age),表结构如下:
mysql> desc student;
+-------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(100) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
+-------+--------------+------+-----+---------+----------------+
3 rows in set (0.01 sec)
3.查看下该新建的表有无内容(用select语句)
4.往新建的student表中插入数据(用insert语句),结果应如下所示:
+----+-------------+------+
| id | name | age |
+----+-------------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
| 8 | chenshuo | 10 |
| 9 | wangwu | 3 |
| 10 | qiuyi | 15 |
| 11 | qiuxiaotian | 20 |
+----+-------------+------+
5.修改lisi的年龄为50
6.以age字段降序排序
7.查询student表中年龄最小的3位同学跳过前2位
8.查询student表中年龄最大的4位同学
9.查询student表中名字叫zhangshan的记录
10.查询student表中名字叫zhangshan且年龄大于20岁的记录
11.查询student表中年龄在23到30之间的记录
12.修改wangwu的年龄为100
13.删除student中名字叫zhangshan且年龄小于等于20的记录