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

1. OS Vendor:操作系统发行商提供的
2. 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