linux——数据库mariadb的基础操作

一、数据库的安装及初始安全配置

[root@localhost ~]# yum install mariadb-server -y
##安装数据库服务软件
##安装过程略
[root@localhost ~]# systemctl start mariadb
[root@localhost ~]# netstat -antlpe | grep mysql      ##列出数据库的工作端口
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN      27         50330      2327/mysqld         
[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# vim /etc/my.cnf
 10 skip-networking=1                                 ##添加第10行，作用直接跳过端口设置，不生成端口
[root@localhost ~]# systemctl restart mariadb
[root@localhost ~]# netstat -antlpe | grep mysql
[root@localhost ~]# mysql                             ##不需密码可以直接进入数据库，不安全
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 2
Server version: 5.5.35-MariaDB MariaDB Server
Copyright (c) 2000, 2013, Oracle, Monty Program Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> quit
Bye
[root@localhost ~]# mysql_secure_installation        ##第一次安装mysql，通过这条命令对mysql进行设置
[root@localhost ~]# mysql -uroot -predhat            
##从本机登录mysql数据库（不建议这种方式，密码可见，不安全）
##进入数据库，-u是登陆用户，-p是用户密码
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 11
Server version: 5.5.35-MariaDB MariaDB Server
Copyright (c) 2000, 2013, Oracle, Monty Program Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> quit
Bye
[root@localhost ~]# mysql -uroot -p   ##从本机登录mysql数据库，此种方式较为安全
Enter password:                       ##输入密码
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 12
Server version: 5.5.35-MariaDB MariaDB Server
Copyright (c) 2000, 2013, Oracle, Monty Program Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> quit
Bye

二、数据库的基本SQL语句

• 以单行或多行书写，以分号结尾

• 可使用空格和缩进来增强语句的可读性

• 书写不区分大小写，建议使用大写，如：SELECT User,Host,Password FROM user;

• 同样可以使用/* */的方式完成注释

1、查询语句

• 查询语句介绍

SHOW DATABASES;     
##查看数据库MySQL服务器中所有的数据库
USE mysql;    
##切换数据库：USE 数据库名
SHOW TABLES;    
##查看数据库中的所有表
SELECT * FROM user;    
##查询user表中的所有字段
SELECT User,Host,Password FROM user;  
##查询user表中的host，user，password字段
SELECT User,Host,Password,Select_priv FROM user;   
##查询user表中的host，user，password,Select_priv字段
DESC user;    
##查看user表的数据结构
SELECT User,Host,Password,Select_priv FROM user Where User='root';  
##查询user表中的User为root的host，user，password,Select_priv字段
##Where [条件]
SELECT User,Host,Password,Select_priv FROM user Where User='root' AND Host='localhost';
##查询user表中的User为root、Host为localhost的host，user，password,Select_priv字段

• 查询语句效果显示

SHOW DATABASES;     ##查看数据库MySQL服务器中所有的数据库

USE mysql;      ##切换数据库：USE 数据库名
SHOW TABLES;    ##查看数据库中的所有表

SELECT * FROM user;                                ##查询user表中的所有字段（命令执行后内容较多，省略不显示）
SELECT User,Host,Password FROM user;               ##查询user表中的host，user，password字段
SELECT User,Host,Password,Select_priv FROM user;   ##查询user表中的host，user，password,Select_priv字段

DESC user;       ##查看user表的数据结构

SELECT User,Host,Password,Select_priv FROM user Where User='root';  
##查询user表中的User为root的host，user，password,Select_priv字段
##Where [条件]
SELECT User,Host,Password,Select_priv FROM user Where User='root' AND Host='localhost';
##查询user表中的User为root、Host为localhost的host，user，password,Select_priv字段

2、数据库以及表的创建

CREATE DATABASE westos;      ##创建数据库westos

CREATE TABLE linux(
    -> username varchar(6) not null,
    -> password varchar(50) not null);    ##创建表，username，password字段
CREATE TABLE linux(username varchar(6) not null,password varchar(50) not null);    ##创建表，username，password字段
##上面两条命令一样，第一条换行，第二条没有换行

INSERT INTO linux value ('tutu','123');  ##在linux表中插入值为username = tutu，password = 123

INSERT INTO linux value ('butter','234');   ##在linux表中插入值为username = butter，password = 234

3、数据库名的更改

• 一般不做更改，更改后，可能会影响数据库的使用
  

[root@localhost ~]# cd /var/lib/mysql/
[root@localhost mysql]# ls
aria_log.00000001  ibdata1      ib_logfile1  mysql.sock          westos
aria_log_control   ib_logfile0  mysql        performance_schema
[root@localhost mysql]# cd westos/
[root@localhost westos]# ls
db.opt  linux.frm
[root@localhost westos]# file linux.frm 
linux.frm: MySQL table definition file Version 10
[root@localhost westos]# file db.opt 
db.opt: ASCII text
[root@localhost westos]# cd ..
[root@localhost mysql]# mv westos/ hello      ##将数据库名称westos更改为hello
[root@localhost mysql]# ls
aria_log.00000001  hello    ib_logfile0  mysql       performance_schema
aria_log_control   ibdata1  ib_logfile1  mysql.sock
[root@localhost mysql]# systemctl restart mariadb

• 结果验证

• 刷新数据库信息——FLUSH PRIVILEGES;
  

[root@localhost mysql]# ls
aria_log.00000001  hello    ib_logfile0  mysql       performance_schema
aria_log_control   ibdata1  ib_logfile1  mysql.sock
[root@localhost mysql]# mv hello/ westos

4、表的修改、添加、删除及数据库的删除

• 表名称的修改（一般不做修改）

ALTER TABLE linux RENAME messages;    ##将表的名称linux改为messages

ALTER TABLE messages RENAME linux;   ##将表的名称messages改回为linux

ALTER TABLE linux ADD age varchar(5);    ##添加age字段到linux表中（默认加到最后一列）
 ALTER TABLE linux DROP age;             ##删除字段age

ALTER TABLE linux ADD age varchar(5) AFTER username;   ##在username字段后添加字段age
ALTER TABLE linux DROP age;                            ##删除字段age

UPDATE linux SET username='hello' WHERE password='123';     ##更新linux表中password是123的username信息为hello
DELETE FROM linux WHERE username='hello';                   ##将linux表中hello的所有内容

DROP TABLE linux;     ##将linux表删除
DROP DATABASE westos; ##将数据库westos删除

4、HTTP 和 PHP 对于数据库的管理

• HTTP 和 PHP 的前期准备

[root@localhost ~]# yum install httpd php -y
##安装httpd和php，安装过程略
[root@localhost ~]# systemctl start httpd
[root@localhost ~]# cd /var/www/html/
[root@localhost html]# ls
phpMyAdmin-3.4.0-all-languages.tar.bz2   ##从网上可以下载该压缩包
[root@localhost html]# tar jxf phpMyAdmin-3.4.0-all-languages.tar.bz2 
[root@localhost html]# ls
phpMyAdmin-3.4.0-all-languages  phpMyAdmin-3.4.0-all-languages.tar.bz2
[root@localhost html]# rm -fr phpMyAdmin-3.4.0-all-languages.tar.bz2 
[root@localhost html]# mv phpMyAdmin-3.4.0-all-languages mysqladmin   ##更改目录名称
[root@localhost html]# ls
mysqladmin
[root@localhost html]# cd mysqladmin/
[root@localhost mysqladmin]# ls | grep config.sample.
config.sample.inc.php
[root@localhost mysqladmin]# cp config.sample.inc.php config.inc.php 
[root@localhost mysqladmin]# ls | grep config
config.inc.php
config.sample.inc.php
show_config_errors.php

此时用浏览器访问http://172.25.254.127/mysqladmin      ##访问失败，因为 php 中不存在 mysql

[root@localhost mysqladmin]# php -m | grep mysql
[root@localhost mysqladmin]# yum search php
Loaded plugins: langpacks
=========================================== N/S matched: php ===========================================
php.x86_64 : PHP scripting language for creating dynamic web sites
php-cli.x86_64 : Command-line interface for PHP
php-common.x86_64 : Common files for PHP
php-gd.x86_64 : A module for PHP applications for using the gd graphics library
php-ldap.x86_64 : A module for PHP applications that use LDAP
php-mysql.x86_64 : A module for PHP applications that use MySQL databases
php-odbc.x86_64 : A module for PHP applications that use ODBC databases
php-pdo.x86_64 : A database access abstraction module for PHP applications
php-pear.noarch : PHP Extension and Application Repository framework
php-pgsql.x86_64 : A PostgreSQL database module for PHP
php-process.x86_64 : Modules for PHP script using system process interfaces
php-recode.x86_64 : A module for PHP applications for using the recode library
php-soap.x86_64 : A module for PHP applications that use the SOAP protocol
php-xml.x86_64 : A module for PHP applications which use XML
php-xmlrpc.x86_64 : A module for PHP applications which use the XML-RPC protocol
php-pecl-memcache.x86_64 : Extension to work with the Memcached caching daemon
  Name and summary matches only, use "search all" for everything.
[root@localhost mysqladmin]# yum install php-mysql.x86_64 -y
##安装过程略
[root@localhost mysqladmin]# php -m | grep mysql
mysql
mysqli
pdo_mysql
[root@localhost mysqladmin]# systemctl restart httpd

此时用浏览器访问http://172.25.254.127/mysqladmin

MariaDB [(none)]> SHOW DATABASES;    ##此时还没有数据库westos
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
+--------------------+
3 rows in set (0.00 sec)

MariaDB [(none)]> SHOW DATABASES;    ##在浏览器中创建数据库westoos成功后
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| westos             |
+--------------------+
4 rows in set (0.00 sec)

MariaDB [(none)]> USE westos;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
MariaDB [westos]> SHOW TABLES;    ##此时还没有新建数据表
Empty set (0.00 sec)

MariaDB [westos]> SHOW TABLES;    ##数据表创建成功后
+------------------+
| Tables_in_westos |
+------------------+
| linux            |
+------------------+
1 row in set (0.00 sec)

MariaDB [westos]> SELECT * FROM linux;    ##创建字段前
Empty set (0.00 sec)

MariaDB [westos]> SELECT * FROM linux;    ##创建字段后
+----------+-----------+-------+
| username | password  | class |
+----------+-----------+-------+
| tutu     | tutu123   | linux |
| root     | redhat123 | linux |
+----------+-----------+-------+
2 rows in set (0.00 sec)

MariaDB [westos]> SELECT * FROM linux;    ##修改字段后
+----------+-----------+-------+
| username | password  | class |
+----------+-----------+-------+
| tutu     | tutu456   | linux |
| root     | redhat123 | linux |
+----------+-----------+-------+
2 rows in set (0.00 sec)

5、用户的创建、授权、删除等

• CREATE USER tutu@'localhost' identified by 'tutu';

##创建用户tutu，'localhost'代表用户tutu只能在本地登陆，'%'代表用户tutu能远程登陆，identified by 'tutu'设置登陆密码为tutu

[root@localhost mysqladmin]# mysql -uroot -p
Enter password: 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 72
Server version: 5.5.35-MariaDB MariaDB Server
Copyright (c) 2000, 2013, Oracle, Monty Program Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]>     

• GRANT SELECT on westos.* to tutu@localhost;

##添加用户tutu对于数据库westos的查看权限

• GRANT UPDATE on westos.* to tutu@localhost;

##添加用户tutu对于数据库westos的写权限（此处不进行效果演示）

##此权限是让用户tutu可以对数据库westos进行编辑

• 用户权限及用户的删除

6、密码修改

• mysqladmin -uroot -predhat password 'tutu'            ##修改本地 mysql root 密码 redhat 为 westos

[root@localhost mysqladmin]# mysql -uroot -predhat password 'tutu'
[root@localhost mysqladmin]# mysql -uroot -predhat
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

• mysqladmin -uroot -predhat -h ip password westos    ##修改远程ip mysql服务器 root密码

• ###当超级用户密码忘记时###

[root@localhost mysqladmin]# systemctl stop mariadb
[root@localhost mysqladmin]# mysqld_safe --skip-grant-tables &    ##跳过grant-tables授权表  不需要认证登录本地mysql数据库
[1] 6141
[root@localhost mysqladmin]# 180526 02:42:44 mysqld_safe Logging to '/var/log/mariadb/mariadb.log'.
180526 02:42:44 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
[root@localhost mysqladmin]# mysql
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 1
Server version: 5.5.35-MariaDB MariaDB Server
Copyright (c) 2000, 2013, Oracle, Monty Program Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> SELECT Host,User,Password FROM mysql.user;
+-----------+------+-------------------------------------------+
| Host      | User | Password                                  |
+-----------+------+-------------------------------------------+
| localhost | root | *23AE809DDACAF96AF0FD78ED04B6A265E05AA257 |
| 127.0.0.1 | root | *23AE809DDACAF96AF0FD78ED04B6A265E05AA257 |
| ::1       | root | *23AE809DDACAF96AF0FD78ED04B6A265E05AA257 |
+-----------+------+-------------------------------------------+
3 rows in set (0.00 sec)
MariaDB [(none)]> update mysql.user set Password=password('123') where User='root'; 
##更新mysql.user 表中条件为root用户的密码为加密tutu
Query OK, 3 rows affected (0.00 sec)
Rows matched: 3  Changed: 3  Warnings: 0
MariaDB [(none)]> SELECT Host,User,Password FROM mysql.user;
+-----------+------+-------------------------------------------+
| Host      | User | Password                                  |
+-----------+------+-------------------------------------------+
| localhost | root | *6D80C637B84CD462FED1542FD0425E3ABF536C90 |
| 127.0.0.1 | root | *6D80C637B84CD462FED1542FD0425E3ABF536C90 |
| ::1       | root | *6D80C637B84CD462FED1542FD0425E3ABF536C90 |
+-----------+------+-------------------------------------------+
3 rows in set (0.00 sec)
MariaDB [(none)]> quit
Bye
[root@localhost mysqladmin]# fg
mysqld_safe --skip-grant-tables
^Z
[1]+  Stopped                 mysqld_safe --skip-grant-tables
[root@localhost mysqladmin]# killall -9 mysqld_safe
[1]+  Killed                  mysqld_safe --skip-grant-tables
[root@localhost mysqladmin]# ps aux | grep mysql
mysql     6296  0.0 10.1 859068 98256 pts/1    Sl   02:42   0:00 /usr/libexec/mysqld···（比较长，删除了一些）
root      6371  0.0  0.0 112640   936 pts/1    R+   02:48   0:00 grep --color=auto mysql
[root@localhost mysqladmin]# kill -9 6296
[root@localhost mysqladmin]# ps aux | grep mysql
root      6373  0.0  0.0 112640   940 pts/1    R+   02:48   0:00 grep --color=auto mysql
[root@localhost mysqladmin]# systemctl start mariadb
[root@localhost mysqladmin]# mysql -uroot -ptutu
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 2
Server version: 5.5.35-MariaDB MariaDB Server
Copyright (c) 2000, 2013, Oracle, Monty Program Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> quit
Bye
[root@localhost mysqladmin]# 

7、数据库的备份

[root@localhost mysqladmin]# mysql -uroot -ptutu -e "show databases;"
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| westos             |
+--------------------+
[root@localhost mysqladmin]# mysql -uroot -ptutu
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 107
Server version: 5.5.35-MariaDB MariaDB Server
Copyright (c) 2000, 2013, Oracle, Monty Program Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> quit
Bye
[root@localhost mysqladmin]# mysqldump -uroot -ptutu --all-database
##内容略，备份框架以及内容
[root@localhost mysqladmin]# mysqldump -uroot -ptutu --all-database --no-data
##内容略，只备份框架
[root@localhost mysqladmin]# mysqldump -uroot -ptutu westos > /mnt/westos.sql   ##备份数据库westos到/mnt/下，命名为westos.sql
[root@localhost mysqladmin]# mysql -uroot -ptutu -e "drop database westos;"     ##删除数据库westos
[root@localhost mysqladmin]# mysql -uroot -ptutu -e "show databases;"
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
+--------------------+
[root@localhost mysqladmin]# ls /mnt/
westos.sql
[root@localhost mysqladmin]# vim /mnt/westos.sql     
 21 CREATE DATABASE westos;            ##添加第21、22行
 22 USE westos;
[root@localhost mysqladmin]# mysql -uroot -ptutu < /mnt/westos.sql 
[root@localhost mysqladmin]# mysql -uroot -ptutu -e "select * from westos.linux;"
+----------+-----------+-------+
| username | password  | class |
+----------+-----------+-------+
| tutu     | tutu456   | linux |
| root     | redhat123 | linux |
+----------+-----------+-------+
[root@localhost mysqladmin]# mysql -uroot -ptutu -e "drop database westos;"
[root@localhost mysqladmin]# mysql -uroot -ptutu -e "select * from westos.linux;"
ERROR 1146 (42S02) at line 1: Table 'westos.linux' doesn't exist
[root@localhost mysqladmin]# vim /mnt/westos.sql     
 21 /*CREATE DATABASE westos;*/            ##注释掉第21、22行
 22 /*USE westos;*/
[root@localhost mysqladmin]# mysql -uroot -ptutu -e "CREATE DATABASE westos;"
[root@localhost mysqladmin]# mysql -uroot -ptutu westos < /mnt/westos.sql 
[root@localhost mysqladmin]# mysql -uroot -ptutu -e "select * from westos.linux;"
+----------+-----------+-------+
| username | password  | class |
+----------+-----------+-------+
| tutu     | tutu456   | linux |
| root     | redhat123 | linux |
+----------+-----------+-------+
[root@localhost mysqladmin]#