设置更改root密码（远程，本地）、连接mysql、mysql常用命令

设置更改root密码
1、将mysql加入环境变量中
[root@centos7 ~]# grep mysql /etc/profile
export PATH=/usr/local/mysql/bin/:$PATH

2、直接登录，无密码
[root@centos7 ~]# mysql -uroot
3、方式一：设置密码
[root@centos7 ~]# mysqladmin -uroot password '123456'
Warning: Using a password on the command line interface can be insecure.
You have new mail in /var/spool/mail/root
方式二：设置远程密码和本地密码

远程密码：远程主机登录使用
本地密码：只能本机登录使用
mysql> set password for 'root'@'localhost'=password('root'); #本地密码
Query OK, 0 rows affected (0.01 sec)

mysql> GRANT USAGE ON *.* TO 'root'@'%' IDENTIFIED BY '123456'; #远程密码
Query OK, 0 rows affected (0.00 sec)

查看：
mysql> select Host,User from mysql.user;



备注：（直接输入mysql就可以登录）
vi /etc/my.cnf
[client]
port = 3306
user=root
password=root

4、登录

[root@centos7 ~]# mysql -uroot -p'123456' -h127.0.0.1 -P3306
-h：指定主机
-P：指定端口
5、更改密码为1234
[root@centos7 ~]# mysqladmin -uroot -p'123456' password '1234'

忘记密码后，怎么更改？
1、[root@centos7 ~]# vi /etc/my.cnf
[mysqld]
skip-grant#跳过授权登录
2、重启mysql服务
[root@centos7 ~]# /etc/init.d/mysqld restart
3、[root@centos7 ~]# mysql -uroot
mysql> use mysql;
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
mysql> update user set password=password('123456') where user='root'; #更改密码
4、将skip-grant配置删除后重启mysql服务
/etc/init.d/mysqld restart
5、已更改密码

连接mysql
1、[root@centos7 ~]# mysql -uroot -p123456 -h127.0.0.1 -P3306
2、通过socket连接
[root@centos7 ~]# mysql -uroot -p123456 -S/tmp/mysql.sock

mysql常用命令
1、显示所有数据库
show databases;
2、进入哪个数据库
user db
3、显示数据库中所有的表
mysql> show tables;
4、显示表结构（由什么字段组成）
desc user;
5、查询
select host,user from user;
6、显示建表语句过程
show create table user\G;
7、显示哪个用户登录
select user();
8、显示表有多少行
select count(*) from user ;
9、显示变量

show variables;
10、查找
show variables like '%error%';
11、设置临时变量
mysql> set global max_connect_errors = 1000;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like 'max_connect_errors';
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| max_connect_errors | 1000 |
+--------------------+-------+
11、显示mysql的进程队列

mysql> show processlist;
+----+------+-----------+-------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+-------+---------+------+-------+------------------+
| 3 | root | localhost | mysql | Query | 0 | init | show processlist |
+----+------+-----------+-------+---------+------+-------+------------------+
1 row in set (0.01 sec)

mysql> show full processlist; #完整情况
+----+------+-----------+-------+---------+------+-------+------------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+-------+---------+------+-------+------------------------+
| 3 | root | localhost | mysql | Query | 0 | init | show full processlist |
+----+------+-----------+-------+---------+------+-------+------------------------+
12、新建表，字段
mysql> create table tb(`id` int,`num` varchar(10));
Query OK, 0 rows affected (0.02 sec)

mysql> show tables
-> ;
+----------------+
| Tables_in_test |
+----------------+
| tb |
+----------------+
1 row in set (0.00 sec)

mysql> show create table tb;
+-------+--------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+--------------------------------------------------------------------------------------------------------------------------+
| tb | CREATE TABLE `tb` (
`id` int(11) DEFAULT NULL,
`num` varchar(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+--------------------------------------------------------------------------------------------------------------------------+

mysql> desc tb;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| num | varchar(10) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
13、删除库及表

drop database test;
drop table tb;
14、插入数据
insert tb value(1,4);