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 tcp 0 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 line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or g. Your MySQL connection id is 5 Server version: 5.7.20-0ubuntu0.16.04.1 (Ubuntu) Copyright (c) 2000, 2017, 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> show databases; #初始有四个数据库 +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | performance_schema | | sys | +--------------------+ 4 rows in set (0.16 sec)
创建用户并授权：
mysql> create user 'l'@'%' identified by '123'; Query OK, 0 rows affected (0.09 sec) mysql> select user,host from user; +---------------+-----------+ | user | host | +---------------+-----------+ | l | % | | mysql.session | localhost | | mysql.sys | localhost | | root | localhost | +---------------+-----------+ 4 rows in set (0.00 sec) 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