13.1 设置更改root密码
设置更改root密码目录概要
/usr/local/mysql/bin/mysql -uroot 更改环境变量PATH，增加mysql绝对路径 mysqladmin -uroot password '123456' mysql -uroot -p123456 密码重置 vi /etc/my.cnf//增加skip-grant 重启mysql服务 /etc/init.d/mysqld restart mysql -uroot use mysql; update user set password=password('aminglinux') where user='root';
设置更改root密码
root用户是mysql的超级管理员用户，和linux系统的root用户类似，不过和Linux的不一样
默认mysql的 root 用户密码是空的，直接使用mysql -uroot就可以连接上去，不需要输入密码，但是不安全，所以就需要设置一个密码
为了方便使用mysql服务，将mysql目录加入到环境变量里"export PATH=/usr/local/mysql/bin:$PATH" 永久生效加入到"/etc/profile"里面，执行source /etc/profile 命令
1、查看mysql是否启动 ps aux|grep mysql，如果没有启动，执行"/etc/init.d/mysqld start"
[root@lnmp-server ~]# ps aux |grep mysql
root 841 0.0 0.1 115432 1728 ? S 10:33 0:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/data/mysql/ --pid-file=/data/mysql//lnmp-server.pid
mysql 1057 6.4 45.1 1296356 451644 ? Sl 10:33 0:04 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/data/mysql --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=/var/log/mysqld.log --pid-file=/data/mysql//lnmp-server.pid --socket=/tmp/mysql.sock --port=3306
root 1231 0.0 0.0 112720 972 pts/0 R+ 10:34 0:00 grep --color=auto mysql
2、设置mysql的root密码 安装完mysql后，默认root用户是没有密码的，我们可以通过mysql自带的命令mysqladmin给root设置一个密码 格式：**mysqladmin -uroot passwd '123456' **
[root@lnmp-server ~]# mysqladmin -uroot password '123456'
Warning: Using a password on the command line interface can be insecure.
在设置密码的时候，会看到有输出信息，但这不是报错信息，这是告诉你 你现在密码在当前命令行显示出来了，这样不×××全 3、知道密码的情况下更改密码 格式：mysqladmin -uroot -p'123456' password '654321'
[root@lnmp-server ~]# mysqladmin -uroot -p'123456' password '654321'
Warning: Using a password on the command line interface can be insecure.
4、忘记密码的情况修改 第一步：修改mysql的配置文件 /etc/my.cnf 在mysqld模块下加入一行skip-grant,表示忽略授权
vi /etc/my.cnf #在mysqld模块下新增一行
skip-gant
[root@lnmp-server ~]# cat /etc/my.cnf
[mysqld]
port = 3306
basedir=/usr/local/mysql
datadir=/data/mysql/
socket=/tmp/mysql.sock
user=mysql
default-time-zone=system
default-storage-engine=InnoDB
log-error=/var/log/mysqld.log
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
skip-grant #增加这一行
第二步：在更改配置文件后，重启mysql服务 /etc/init.d/mysqld restart
[root@lnmp-server ~]# /etc/init.d/mysqld restart
Shutting down MySQL. SUCCESS!
Starting MySQL. SUCCESS!
第三步：连接mysql,这时候在输入mysql -uroot ，会发现直接进入mysql，而不需要密码了
[root@lnmp-server ~]# mysql -uroot
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.36 Source distribution
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>
第四步：更新密码，进入mysql后，输入：update mysql.user set password=password('123456') where user='root';
mysql> update mysql.user set password=password('123456') where user='root';
Query OK, 0 rows affected (0.06 sec)
Rows matched: 4 Changed: 4 Warnings: 0
mysql> flush privileges; #刷新权限，让它生效
Query OK, 0 rows affected (0.00 sec)
mysql> quit #输入quit,退出mysql
Bye
注：提示说4行修改完毕，即使有些行是空的 第五步：更新完后修改mysql的配置文件 /etc/my.cnf 删除增加的那一行skip-grant，去掉忽略授权，并重启mysql服务 /etc/init.d/mysqld restart
[root@lnmp-server ~]# cat /etc/my.cnf
[mysqld]
port = 3306
basedir=/usr/local/mysql
datadir=/data/mysql/
socket=/tmp/mysql.sock
user=mysql
default-time-zone=system
default-storage-engine=InnoDB
log-error=/var/log/mysqld.log
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
#skip-grant #这一行删掉或者注释掉
第六步：用更新完后密码登陆mysql -uroot -p'123456'
[root@lnmp-server ~]# mysql -uroot -p'123456'
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 3
Server version: 5.6.36 Source distribution
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>
13.2 连接mysql
1、本地连接，默认使用sock连接 格式：mysql -uroot -p‘123456’
[root@lnmp-server ~]# mysql -uroot -p'123456'
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 3
Server version: 5.6.36 Source distribution
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>
2、使用ip端口连接远程机器 格式：mysql -uroot -p'111111' -h[远程mysql主机IP] -P[端口]，mysql默认端口3306
[root@lnmp-server ~]# mysql -uroot -p'123456' -h127.0.0.1 -P3306
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: 5.6.36 Source distribution
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>
3、指定sock文件（只适合本机登陆） 格式：mysql -uroot -p'123456' -S/tmp/mysql.sock
[root@lnmp-server ~]# mysql -uroot -p'123456' -S/tmp/mysql.sock
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: 5.6.36 Source distribution
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>
4、不登陆mysql执行sql语句（常用于shell脚本） 格式：mysql -uroot -p123456 -e 'show databases;'
[root@lnmp-server ~]# mysql -uroot -p'123456' -e 'show databases;'
Warning: Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
13.3 mysql常用命令
查询库 show databases; 切换库 use mysql; 查看库里的表 show tables; 查看表里的字段 desc tb_name; 查看建表语句 show create table tb_name\G; 查看当前用户 select user(); 查看当前使用的数据库 select database(); 创建库 create database db1; 创建表 use db1; create table t1(id int(4), name char(40)); 查看当前数据库版本 select version(); 查看数据库状态 show status; 查看各参数 show variables; show variables like 'max_connect%'; 修改参数 set global max_connect_errors=1000; 查看队列 show processlist; show full processlist;
1、创建库db1，并查看库
mysql> create database db1;
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| db1 |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec)
2、使用db1库,创建表tb1（新建字段id 整数型长度为4 ，字段name 字符型长度为40）,并查看表
mysql> use db1;
Database changed
mysql> create table tb1 (id int(4),name char(40));
Query OK, 0 rows affected (0.13 sec)
mysql> show tables;
+---------------+
| Tables_in_db1 |
+---------------+
| tb1 |
+---------------+
1 row in set (0.00 sec)
3、查看表的字段
mysql> desc tb1;
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id | int(4) | YES | | NULL | |
| name | char(40) | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)
4、查看建表语句
mysql> show create table tb1\G;
*************************** 1. row ***************************
Table: tb1
Create Table: CREATE TABLE `tb1` (
`id` int(4) DEFAULT NULL,
`name` char(40) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)
ERROR:
No query specified
注：\G是为了竖型显示，更清晰 5、查看当前用户和库
mysql> select user();
+----------------+
| user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> select database();
+------------+
| database() |
+------------+
| db1 |
+------------+
1 row in set (0.00 sec)
6、查询数据库版本
mysql> select version();
+-----------+
| version() |
+-----------+
| 5.6.36 |
+-----------+
1 row in set (0.00 sec)
7、查看各参数 show variables; show variables like 'max_connect%'; // mysql下 % 为通配符
mysql> show variables like 'max_connect%';
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| max_connect_errors | 100 |
| max_connections | 151 |
+--------------------+-------+
2 rows in set (0.00 sec)
8、修改参数 set global max_connect_errors=1000; ——>仅在内存中生效，若想重启生效修改/etc/my.cnf
mysql> set global max_connect_errors=1000;
Query OK, 0 rows affected (0.00 sec)
mysql> show variables like 'max_connect%';
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| max_connect_errors | 1000 |
| max_connections | 151 |
+--------------------+-------+
2 rows in set (0.00 sec)
9、查看队列 show processlist; //查看库的状况，比如，那些用户在连，做了些什么操作，是否锁表 show full processlist; //查看到的对列，最后一个会非常完成的显示出来
mysql> show processlist;
+----+------+-----------+------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+------+---------+------+-------+------------------+
| 14 | root | localhost | db1 | Query | 0 | init | show processlist |
+----+------+-----------+------+---------+------+-------+------------------+
1 row in set (0.00 sec)
mysql> show full processlist;
+----+------+-----------+------+---------+------+-------+------------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+------+---------+------+-------+------------------------+
| 14 | root | localhost | db1 | Query | 0 | init | show full processlist |
+----+------+-----------+------+---------+------+-------+------------------------+
1 row in set (0.00 sec)
说明：在mysql中也支持上下方向键查看执行过的命令，命令历史保存在用户家目录下.mysql_history文件中
13.4 mysql用户管理
1、创建一个用户并授权所有库和表的所有权限 格式：grant all on . to 'user1' identified by 'passwd';
mysql> grant all on *.* to 'luo' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
mysql> select user from mysql.user;
+------+
| user |
+------+
| luo |
| root |
| root |
| |
| root |
| |
| root |
+------+
7 rows in set (0.00 sec)
2、针对指定的条件授权 格式：grant SELECT,UPDATE,INSERT on db1.* to 'user2'@'192.168.180.1' identified by 'passwd'; 语句说明：授权查询 更新 插入 在数据库 db1所有表上 给来源ip为192.168.180.1的用户user2，并设定密码
mysql> grant SELECT,UPDATE,INSERT on db1.* to 'user2'@'192.168.133.132' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
3、针对指定的条件授权 格式：grant all on db1.* to 'user3'@'%' identified by 'passwd'; 语句说明：授权所有权限在数据库 db1所有表上 给来源ip为所有的用户user2，并设定密码 ，%表示通配，即所有的
mysql> grant all on db1.* to 'user2'@'%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
4、show grants; show grants；看的是root
mysql> show grants;
+----------------------------------------------------------------------------------------------------------------------------------------+
| Grants for root@localhost |
+----------------------------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED BY PASSWORD '*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION |
+----------------------------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
5、查看刚才授权的用户user2@'192.168.133.132'
mysql> show grants for 'user2'@'192.168.133.132';
+--------------------------------------------------------------------------------------------------------------------+
| Grants for user2@192.168.133.132 |
+--------------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'user2'@'192.168.133.132' IDENTIFIED BY PASSWORD '*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9' |
| GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user2'@'192.168.133.132' |
+--------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
13.5 常用sql语句
增删改查，就是mysql和其他关系型数据库常用的select语句操作命令 查询语句
首先登录root下的mysql mysql -uroot -p111111 使用db1库 use db1; 查看当前库的所有表show tables; 查看表的行数 select count(*) from mysql.user; 库和表中间有个分割符，就是用点 . 分割
mysql> select count(*) from mysql.user;
+----------+
| count(*) |
+----------+
| 10 |
+----------+
1 row in set (0.00 sec)
就是说user表有10行内容 查看所有的内容 select * from mysql.db;（这样看起来会很乱） ——>可以在后面加上\G，如select * from mysql.db\G; 这里的 * 表示查看所有内容 查看db库的所有内容 select db from mysql.db; 第一个db是字段
mysql> select db from mysql.db;
+---------+
| db |
+---------+
| test |
| test\_% |
| db1 |
| db1 |
+---------+
4 rows in set (0.01 sec)
查db字段和user字段 select db,user from mysql.db;
mysql> select db,user from mysql.db;
+---------+-------+
| db | user |
+---------+-------+
| test | |
| test\_% | |
| db1 | user2 |
| db1 | user2 |
+---------+-------+
4 rows in set (0.00 sec)
模糊查询 select * from mysql.db where host like '192.168.%'; like 就是模糊匹配 插入语句
查看创建的表
mysql> desc db1.tb1;
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id | int(4) | YES | | NULL | |
| name | char(40) | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)
查看db1.tb1表的内容，会发现为空 select * from db1.tb1; 插入数据到
insert into db1.tb1 values (1, 'abc');`
插入1, 'abc'到db1.tb1表 再来查询db1.tb1
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 1 | abc |
+------+------+
1 row in set (0.00 sec)
这样就成功了插入了一条数据，在插入的时候 name 这个字段应该是是一个字符串，字符串需要加上一个单引号 ' ' ，数字可以不加单引号
mysql> insert into db1.tb1 values (1, 234);
Query OK, 1 row affected (0.01 sec)
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 1 | abc |
| 1 | 234 |
+------+------+
2 rows in set (0.00 sec)
这里没有做限制，这里id和name都可以是相同的，同一个字段里有相同的数字，相同的值 ，也可以做一些限制，在插入相同的id的时候，就会冲突 update操作
更改db1.t1表 的字符串为name 的数据 和 字符串为id 的数据 update db1.tb1 set name='aaa' where id=1;
mysql> update db1.tb1 set name='aaa' where id=1;
Query OK, 2 rows affected (0.01 sec)
Rows matched: 2 Changed: 2 Warnings: 0
mysql> select * from db1.tb1;
+------+------+
| id | name |
+------+------+
| 1 | aaa |
| 1 | aaa |
+------+------+
2 rows in set (0.00 sec)
delete操作
删除db1.tb1表 的数据 和 字符串为id 的数据
delete from db1.t1 where id=1;
mysql> delete from db1.tb1 where id=1;
Query OK, 2 rows affected (0.01 sec)
mysql> select * from db1.tb1;
Empty set (0.00 sec)
truncate清空一个表
清空表数据 truncate table db1.tb1; 即使表的数据清空了，但表的字段依旧存在的
mysql> truncate table db1.tb1;
Query OK, 0 rows affected (0.02 sec)
mysql> select * from db1.tb1;
Empty set (0.00 sec)
mysql> desc db1.tb1;
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id | int(4) | YES | | NULL | |
| name | char(40) | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)
truncate 只是清空的内容，而drop 会清空表的数据并清除表的框架 drop 会把表的框架也丢掉 drop table db1.tb1;
mysql> drop table db1.tb1;
Query OK, 0 rows affected (0.01 sec)
mysql> select * from db1.tb1; //因为表的架构已经不存在了
ERROR 1146 (42S02): Table 'db1.t1' doesn't exist
mysql>
删除库
drop database db1;
总结
在使用mysql的时候，少用 * 这样的操作，因为若是一个表里面的内容很多，select count()这样操作就会很耗时，浪费资源 数据库中常用引擎是myisam和innodb，默认mysql库里面都是使用的myisam引擎 特点：myisam引擎，能自动去统计有多少行 在select count()查看表的时候会很快 use mysql; show create table user\G; 特点：innodb引擎，不会自动统计行数，每次去查询，每次去统计行数，就会很耗时 use db1 show create table t1; 所以select count(*)这种操作尽量减少，会耗费太多资源
13.6 mysql数据库备份恢复
备份库 备份mysql库 mysqlbak.sql文件就是mysql的备份库文件
[root@lnmp-server ~]# mysqldump -uroot -p123456 mysql>/tmp/mysqlbak.sql
Warning: Using a password on the command line interface can be insecure.
[root@lnmp-server ~]# ll /tmp/mysqlbak.sql
-rw-r--r-- 1 root root 657033 7月 12 13:14 /tmp/mysqlbak.sql
我们可以通过mysqlbak.sql来恢复数据库，还可以恢复到另外一个数据库里面去 恢复库 这里把数据恢复到新的库里，创建一个新的库mysql2
[root@lnmp-server ~]# mysql -uroot -p123456 -e "create database mysql2;"
Warning: Using a password on the command line interface can be insecure.
[root@lnmp-server ~]# mysql -uroot -p123456 mysql2 </tmp/mysqlbak.sql
Warning: Using a password on the command line interface can be insecure.
进入到数据库里面，在后面加一个mysql2 就会进入到mysql2数据库里面
[root@lnmp-server ~]# mysql -uroot -p123456 mysql2
Warning: Using a password on the command line interface can be insecure.
查看数据库
mysql> select database();
+------------+
| database() |
+------------+
| mysql2 |
+------------+
1 row in set (0.00 sec)
备份表 针对库里面的某一个表去做备份，只需要在 库后面 加上 表名字 即可备份,先库 在表，中间是空格 备份表格式：mysqldump -uroot -p123456 databasename tablename > /tmp/user.sql
[root@lnmp-server ~]# mysqldump -uroot -p123456 mysql user >/tmp/user.sql
Warning: Using a password on the command line interface can be insecure.
恢复表 恢复表的时候，只需要写库的名字，不需要去写表的名字 恢复表格式：mysql -uroot -p123456 mysql < /tmp/user.sql
[root@lnmp-server ~]# mysql -uroot -p123456 mysql </tmp/user.sql
Warning: Using a password on the command line interface can be insecure.
恢复表到mysql2库
[root@lnmp-server ~]# mysql -uroot -p123456 mysql2 </tmp/user.sql
Warning: Using a password on the command line interface can be insecure.
备份所有的库 格式：mysqldump -uroot -p123456 -A >/tmp/mysql_all.sql -A 表示all所有的意思
[root@lnmp-server ~]# mysqldump -uroot -p111111 -A >/tmp/mysql_all.sql
Warning: Using a password on the command line interface can be insecure.
只备份表结构 格式：mysqldump -uroot -p123456 -d mysql > /tmp/mysql.sql 不需要表的数据，只需要表的结构 备份mysql2的表结构
[root@lnmp-server ~]# mysqldump -uroot -p123456 -d mysql2 > /tmp/mysql2.sql
Warning: Using a password on the command line interface can be insecure.
两个机器的库备份，一个库备份到另一台机器上 解决： 首先两台机器能够通信 然后mysqldump -h 远程mysql-ip -uuser-ppassword dbname > /本地backup.sql 这样即可备份
扩展： 使用xtrabackup备份innodb引擎的数据库 innobackupex 备份 Xtrabackup 增量备份 http://zhangguangzhi.top/2017/08/23/innobackex%E5%B7%A5%E5%85%B7%E5%A4%87%E4%BB%BDmysql%E6%95%B0%E6%8D%AE/#%E4%B8%89%E3%80%81%E5%BC%80%E5%A7%8B%E6%81%A2%E5%A4%8Dmysql mysql5.7 root密码更改 http://www.apelearn.com/bbs/thread-7289-1-1.html myisam 和innodb引擎对比 http://www.pureweber.com/article/myisam-vs-innodb/ mysql 配置详解： http://blog.linuxeye.com/379.html mysql调优： http://www.aminglinux.com/bbs/thread-5758-1-1.html 同学分享的亲身mysql调优经历： http://www.apelearn.com/bbs/thread-11281-1-1.html SQL语句教程 http://www.runoob.com/sql/sql-tutorial.html 什么是事务？事务的特性有哪些？ http://blog.csdn.net/yenange/article/details/7556094
