最近想安装5.7.18 MySQL Community Server 来玩一玩，但安装复杂了好多，尤其在为root用户设置密码这块，就是不能设置简单的123456，我只是测试学习，不需要为了安全弄个16位，32位的MD5码什么的，之前老版本5.5左右的只要下载安装server和client，但是世道变了...
一、系统自带mysql-lib(系统自带的版本过低)
查看系统自带的mysql，什么都没有的话就算了，跳过该步
rpm -qa | grep mysql
但是出现自带的mysql
mysql-libs-5.1.73-3.el6_5.x86_64```
卸载它
`yum remove mysql-libs`
## 二、rpm依赖关系
那么我们进入正题，首先是各个rpm安装包的**依赖关系**，很明显，新的5.7版本需要下载很多rpm,我直接下了个bundle
解压到centos6.5中 的/opt目录下，有这么多包：
怎么解压我就不细说了，重点是这里：
rpm -ivh mysql-community-common-5.7.18-1.el6.x86_64.rpm
rpm -ivh mysql-community-libs-5.7.18-1.el6.x86_64.rpm
rpm -ivh mysql-community-client-5.7.18-1.el6.x86_64.rpm
rpm -ivh mysql-community-server-5.7.18-1.el6.x86_64.rpm
依赖关系就是前面的要是没安装，后面的也否想安装，所以一定要按顺序，（倒是前两个可以互换，忘记吧，当我没说），按顺序，一定要按顺序。
## 三、修改密码（巨坑）
启动mysql 服务
`service mysqld start`
rpm安装mysql后，会自动初始化一个密码，在日志中，密码为：R!/kValB_3k+（安装后随机生成的，别指望这个能用，复制粘贴是没用滴）
[root@localhost ~]# cat /var/log/mysqld.log | more
2016-03-11T01:44:19.913630Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --ex
plicit_defaults_for_timestamp server option (see documentation for more details).
2016-03-11T01:44:22.271099Z 0 [Warning] InnoDB: New log files created, LSN=45790
2016-03-11T01:44:22.584299Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2016-03-11T01:44:23.050146Z 0 [Warning] No existing UUID has been found, so we assume that this is the first
time that this server has been started. Generating a new UUID: c7bf1a6a-e72a-11e5-8737-000c29a05942.
2016-03-11T01:44:23.062259Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cann
ot be opened.
+++++++++++++++++++++++++++++++++++密码在这里+++++++++++++++++++++++++++++++++++++++++++++++++++++++
2016-03-11T01:44:23.093873Z 1 [Note] A temporary password is generated for root@localhost: R!/kValB_3k+
++++++++++++++++++++++++++++++++++密码在这里++++++++++++++++++++++++++++++++++++++++++++++++++++++
2016-03-11T01:44:28.470492Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --ex
plicit_defaults_for_timestamp server option (see documentation for more details).
2016-03-11T01:44:28.471726Z 0 [Note] /usr/sbin/mysqld (mysqld 5.7.11) starting as process 19672 ...
2016-03-11T01:44:28.626135Z 0 [Note] InnoDB: PUNCH HOLE support available
2016-03-11T01:44:28.626205Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2016-03-11T01:44:28.626220Z 0 [Note] InnoDB: Uses event mutexes
2016-03-11T01:44:28.626233Z 0 [Note] InnoDB: GCC builtin __sync_synchronize() is used for memory barrier
当然也可以这样获取
[root@cloud01 opt]# grep "password" /var/log/mysqld.log
2017-05-19T10:04:22.286192Z 1 [Note] A temporary password is generated for root@localhost: R!/kValB_3k+
修改 mysql root密码，由于最新的mysql版本对密码策略有要求，所以必须增加复杂程度才能通过
注意，用刚才的随机密码登陆mysql.
[root@localhost ~]# mysql -uroot -p
Enter password: 此处输入刚才日志文件中:R!/kValB_3k+
Welcome to the MySQL monitor. commands end with ; or \g.
Your MySQL connection id is 14
Server version: 5.7.11
Copyright (c) 2000, 2016, 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.
+++++++++++++++++++++++++设置一个相当复杂的密码++++++++++++++++++++++++
mysql> set password='CodeGalileo@126.com';
Query OK, 0 rows affected (0.15 sec)
mysql> quit;
Bye
但是我只想设置123456为密码，方便自己使用，那么就会这样,
mysql> SET PASSWORD = PASSWORD('123456');
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
解决方案：(想知道为什么，参见这位大神http://www.cnblogs.com/ivictor/p/5142809.html)
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password_length=6;
Query OK, 0 rows affected (0.00 sec)
接下来我就可以设置我超级简单的密码了
mysql> SET PASSWORD=PASSWORD('123456');
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
设置密码的坑就算填了。
【注意】
我们以前启动mysql-server后经常这么设置密码：
mysql -u root password '123456'
**相信我,有时候，就算你登录了mysql，你也建不出表，查询不了,那么你就需要这个方案来改改密码**
## 四、远程连接
默认情况下，mysql只允许locathost本地登陆，用mysql workbentch ，或者JDBC是无法远程登陆的。
root@localhost,代表root只允许本地用户登陆，
所以必须允许root 从任何IP地址登陆。
`mysql> grant all privileges on *.* to 'root'@'%' identified by '123456';`
当然要关闭Linux防火墙
## 五、开机自启
有人会为了练习敲指令的速度，会在每次开机的时候，手动启动mysql-server，我就不会，这事忘了怎么办？
开机自启这样做：
chkconfig mysqld on
## 六、卸载mysql
清除残留：
找
find / -name "mysql
删
rm -rf /var/lib/mysql
删
rm -rf /usr/share/mysql;
查
rpm -qa | grep mysql
至此，我在安装新版的5.7.18MySQL Community 过程中遇到的坑，算是踩一个填一个，没错，我都踩了...
**欢迎大家补充，共同努力降低初学者学习mysql的门槛**
