在centos7上安装mysql：

1 卸载mariadb-lib。

默认centos7上含有mariadb的lib包。卸载它。

[root@USp11 rpm]# rpm -e --nodeps mariadb-libs-5.5.50-1.el7_2.x86_64
[root@USp11 rpm]# 

2 安装mysql各个包。

包括了common-lib/libs/client/server。

[root@USp11 rpm]# rpm -ivh mysql-community-libs-5.7.14-1.el7.x86_64.rpm
warning: mysql-community-libs-5.7.14-1.el7.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Preparing...                          ################################# [100%]
Updating / installing...1:mysql-community-libs-5.7.14-1.el7################################# [100%]
[root@USp11 rpm]#
[root@USp11 rpm]# rpm -ivh mysql-community-client-5.7.14-1.el7.x86_64.rpm
warning: mysql-community-client-5.7.14-1.el7.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Preparing...                          ################################# [100%]
Updating / installing...1:mysql-community-client-5.7.14-1.e################################# [100%]
[root@USp11 rpm]#
[root@USp11 rpm]#
[root@USp11 rpm]# rpm -ivh mysql-community-server-5.7.14-1.el7.x86_64.rpm
warning: mysql-community-server-5.7.14-1.el7.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Preparing...                          ################################# [100%]
Updating / installing...1:mysql-community-server-5.7.14-1.e################################# [100%]
[root@USp11 rpm]# 

3 mysql密码的问题。

安装后会有登录问题。

[root@USp11 rpm]# mysql
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
[root@USp11 rpm]#

其实安装后会生成随机密码并保存在日志中：

[root@USp11 log]# grep -i password /var/log/mysqld.log
2017-05-03T09:43:49.793937Z 1 [Note] A temporary password is generated for root@localhost: 2:reu9r3=8vI

如果不知道密码也有解决方法：

在/etc/my.cnf末尾  加入skip-grant-tables，保存，跳过身份验证。

重启mysql：systemctl restart mysqld。

进入mysql终端修改密码。（use mysql）

mysql> select host,user,authentication_string from user;
+-----------+-----------+-------------------------------------------+
| host      | user      | authentication_string                     |
+-----------+-----------+-------------------------------------------+
| localhost | root      | *4F9B070523AE6DF88F122FDB8A122B9C1BCEEA0F |
| localhost | mysql.sys | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
+-----------+-----------+-------------------------------------------+
2 rows in set (0.01 sec)mysql> update user set authentication_string=password('123456') where user='root';
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 1mysql> 

在/etc/my.cnf末尾  去掉skip-grant-tables，保存。

重启mysql。

进入后会被要求修改密码。

mysql> status
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
mysql> 

修改密码：

mysql> set password = password('123456');
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
mysql> mysql> set password=password('不告诉你');
Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> 

4 mysql字符问题。

查看字符：

mysql> status
--------------
mysql  Ver 14.14 Distrib 5.7.14, for Linux (x86_64) using  EditLine wrapperConnection id:          2
Current database:       mysql
Current user:           root@
SSL:                    Not in use
Current pager:          stdout
Using outfile:          ''
Using delimiter:        ;
Server version:         5.7.14 MySQL Community Server (GPL)
Protocol version:       10
Connection:             Localhost via UNIX socket
Server characterset:    latin1
Db     characterset:    latin1
Client characterset:    utf8
Conn.  characterset:    utf8
UNIX socket:            /var/lib/mysql/mysql.sock
Uptime:                 14 secThreads: 1  Questions: 40  Slow queries: 0  Opens: 127  Flush tables: 1  Open tables: 122  Queries per second avg: 2.857
--------------

mysql> show variables like '%char%';
+--------------------------------------+----------------------------+
| Variable_name                        | Value                      |
+--------------------------------------+----------------------------+
| character_set_client                 | utf8                       |
| character_set_connection             | utf8                       |
| character_set_database               | utf8                       |
| character_set_filesystem             | binary                     |
| character_set_results                | utf8                       |
| character_set_server                 | utf8                       |
| character_set_system                 | utf8                       |
| character_sets_dir                   | /usr/share/mysql/charsets/ |
| validate_password_special_char_count | 1                          |
+--------------------------------------+----------------------------+
9 rows in set (0.00 sec)mysql> 

设置，在/etc/my.cnf中[mysqld]下设置参数：

[mysqld]
character_set_server = utf8

在/etc/my.cnf中的[client]下设置参数：

[client]
default-character-set = utf8