Mysql卸载
yum remove mysql mysql-server mysql-libs compat-mysql51
rm -rf /var/lib/mysql
rm /etc/my.cnf
查看是否还有mysql软件：
rpm -qa|grep mysql
有的话继续删除

Mysql安装
1>若本地没有安装包 能够考虑使用yum命令进行下载
# yum -y install mysql-server
# yum -y install php-mysql
2>安装后，MySQL自己主动启动，默认没实username和password，设置新password
#   /usr/bin/mysqladmin -u root password 'aaaaaa'
[root@luozhonghua ~]#   /usr/bin/mysqladmin -u root password 'aaaaaa'
/usr/bin/mysqladmin: connect to server at 'localhost' failed
error: 'Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)'
Check that mysqld is running and that the socket: '/var/lib/mysql/mysql.sock' exists!
解决：
2.1》/etc/rc.d/init.d/mysqld status 看看mysql是否已经启动
3.2》service mysqld start
3>登录MySQL
>mysql -u root -p
enter password:’aaaaaa’

4>赋权连接的主机
#grant select,insert,update,delete on *.* to root@192.168.1.101  identified by 'aaaaaa'
grant select,insert,update,delete on *.* to root@127.0.0.1  identified by 'aaaaaa';

5>更改默认字符集
# cp my-medium.cnf  /etc/my.cnf
在[client]下增加 default-character-set=utf8
在[mysqld]下增加 default-character-set=utf8
查找安装路径
Rpm -qa | grep mysql
Rpm -ql 包名
[root@luozhonghua charsets]# find /usr -name my-medium.cnf
/usr/share/doc/mysql-server-5.1.73/my-medium.cnf
/usr/share/mysql/my-medium.cnf

#6>设置mysql开机自启动
# vi /etc/rc.local
增加例如以下一行
#/usr/share/mysql/mysql.server start
7>又一次启动MySQL
# /etc/init.d/mysql restart
service mysqld restart

8>測试;

[root@luozhonghua ~]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.1.73 Source distribution

Copyright (c) 2000, 2013, 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> create database xxx
    -> ;
Query OK, 1 row affected (0.06 sec)

mysql> ls
    -> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual th                                                                                at corresponds to your MySQL server version for the right syntax to use near                                                                                 'ls' at line 1
mysql> show databases
    -> ;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| test               |
| xxx                |
+--------------------+
4 rows in set (0.06 sec)

mysql> use xxx;
Database changed
mysql> show database
    -> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual th                                                                                at corresponds to your MySQL server version for the right syntax to use near                                                                                 'database' at line 1
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| test               |
| xxx                |
+--------------------+
4 rows in set (0.01 sec)

mysql> use xxx;
Database changed
mysql> create table test(
    -> int id not null,
    -> varchar(20) name null);
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual th                                                                                at corresponds to your MySQL server version for the right syntax to use near                                                                                 'int id not null,
varchar(20) name null)' at line 2
mysql> show tables;
Empty set (0.00 sec)

mysql> create table dbtest (
    -> id int ,
    -> name varchar);
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual th                                                                                at corresponds to your MySQL server version for the right syntax to use near                                                                                 ')' at line 3
mysql> create table dbtest (
    -> id int,
    -> name varchar(10));
Query OK, 0 rows affected (0.07 sec)

mysql> show tables;
+---------------+
| Tables_in_xxx |
+---------------+
| dbtest        |
+---------------+
1 row in set (0.01 sec)

mysql> drop table xxx;
ERROR 1051 (42S02): Unknown table 'xxx'
mysql> drop table dbtest;
Query OK, 0 rows affected (0.00 sec)

mysql> ls
    -> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual th                                                                                at corresponds to your MySQL server version for the right syntax to use near                                                                                 'ls' at line 1
mysql> show tables;
Empty set (0.00 sec)

mysql>