系统：ubuntu17.04

数据库主要分文档型和服务型两类：

文档型：如sqlite3 (17.04自带/usr/bin/sqlite3)就是一个文件，应用在移动端如手机，pad，家电等

服务型：如mysql有服务端(存储数据)和客户端

mysql数据库是关系型数据库，采用E-R模型即实体-联系(或关系)模型

安装：

sudo apt install mysql-server，需要设置密码：xxx

sudo apt install mysql-client

sudo apt install libmysqlclient-dev

lyb@lyb:~$ sudo netstat -tap |grep mysql

tcp0 0 localhost:mysql *:* LISTEN 5167/mysqld

成功安装

登录：

l@l:~$ mysql -uroot -pxxx

mysql: [Warning] Using a password on the command lineinterfacecan be insecure.

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection idis 5Server version:5.7.20-0ubuntu0.16.04.1(Ubuntu)

Copyright (c)2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracleis 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>show databases;　　#初始有四个数据库+--------------------+

| Database |

+--------------------+

| information_schema |

| mysql |

| performance_schema |

| sys |

+--------------------+

4 rows in set (0.16sec)

创建用户并授权：

mysql> create user 'l'@'%' identified by '123';

Query OK,0 rows affected (0.09sec)

mysql> select user,host fromuser;+---------------+-----------+

| user | host |

+---------------+-----------+

| l | % |

| mysql.session | localhost |

| mysql.sys | localhost |

| root | localhost |

+---------------+-----------+

4 rows in set (0.00sec)

mysql> grant select on study.* to 'l'@'%';

desc  user；　　#显示其中user表的结构，如下：

+------------------------+-----------------------------------+------+-----+-----------------------+-------+

| Field | Type | Null | Key | Default | Extra |

+------------------------+-----------------------------------+------+-----+-----------------------+-------+

| Host | char(60) | NO | PRI | | |

| User | char(32) | NO | PRI | | |

| Select_priv | enum('N','Y') | NO | | N | |

| Insert_priv | enum('N','Y') | NO | | N | |

| Update_priv | enum('N','Y') | NO | | N | |

| Delete_priv | enum('N','Y') | NO | | N | |

| Create_priv | enum('N','Y') | NO | | N | |

| Drop_priv | enum('N','Y') | NO | | N | |

| Reload_priv | enum('N','Y') | NO | | N | |

| Shutdown_priv | enum('N','Y') | NO | | N | |

| max_user_connections | int(11) unsigned | NO | | 0 | |

| plugin | char(64) | NO | | mysql_native_password | |

| authentication_string | text | YES | | NULL | |

| password_expired | enum('N','Y') | NO | | N | |

| password_last_changed | timestamp | YES | | NULL | |

| password_lifetime | smallint(5) unsigned | YES | | NULL | |

| account_locked | enum('N','Y') | NO | | N | |

+------------------------+-----------------------------------+------+-----+-----------------------+-------+

注：字段创建要有数据类型，长度；Null是否为空，NO表示不能为空；PRI表示主键，一般是一个，本表前两个是联合主键

select  字段  from  表

exit；　　#从mysql数据库退出

ps -ef |grep mysql　　#在命令行从所有进程筛选mysql