Common problems in installing mysql in linux environment and using it

Based on the environment is centos 6.8   mysql 5.6.24版本

1.执行命令 service msyql status查看mysqlThe running times wrong：MySQL is not running, but lock file

解决：Removing the lock file,并把该lockSet the file location;

rm  /var/lock/subsys/mysql 

lock file 在 /etc/rc.d/init.d/mysql Set the changelockdir

vi /etc/rc.d/init.d/mysql

2.重启mysql服务的时候 报错:

Starting MySQL........The server quit without updating PID [失败]/usr/local/mysql/data/mysql/hadoop102.pid).

解决：Directly to find the corresponding file viewpid文件,这个hadoop102.pidIs actually an error log file,也有可能叫hadoop102.err(hadoop102这里是你linux主机的名称)

cat   /usr/local/mysql/data/mysql/hadoop102.pid

When I met the specific error message shown in figure：

原因：Actually this is to set the default encoding format I was wrong;

打开   vi /usr/my.cnf 文件（Some of the default configuration file in/etc/my.cnf）

注释掉 default-character-set=utf8Or change the position,写在client下就行

service mysql start  Restart it so that the

In view of the set encoding format added：

[client]下添加：default-character-set=utf8

[mysqld]下添加：character_set_server=utf8

3.启动mysql 服务的时候 报错 can't open the mysql plugin table

解决：Is starting to findmysql 的数据文件. mysql The data files the default location for /var/lib/mysql

Check your configuration file vi  /usr/my.cnf 文件 datadir的配置

My own configuration as  如图

因此针对这个问题,可以有两种解决方式：

1）将/var/lib/mysql  All data files to/usr/local/mysql/data 下 

mv  /var/lib/mysql /usr/local/mysql/data

2）修改my.cnf文件中,数据的存放路径,同时需要修改Mysql启动文件  /etc/rc.d/init.d/mysql  中datadir 

vi my.cnf 添加如下一行

修改MySQL启动脚本/etc/rc.d/init.d/mysql

vi /etc/rc.d/init.d/mysql

添加 datadir=/usr/local/mysql/data/mysql  ,如图

4. 在创建表时 报错[Err] 1071 - Specified key was too long; max key length is 767 byte

原因：MySQL的varchar主键只支持不超过768个字节 或者 768/2=384个双字节 或者 768/3=256个三字节的字段 ,而 GBK是双字节的,UTF-8是三字节的.In the script has three indexes based on the coding forGBK,varchar（500）的字段上,So lead to exceed limit the length of the.

解决：修改默认编码为utf8

[client]下添加：default-character-set=utf8

[mysqld]下添加：character_set_server=utf8

但是需要注意的是,Before change the coding format to create the database will keep creating coding format,So after change the database encoding format,Need to establish a database！

5.在使用socket连接方式  报错：mysql Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

1）可以修改smysql.sock 存放目录（my.cnfSome machines also in/etc/my.cnf下）,Want to find the perform whereis  my.cnf

vi /usr/my.cnf 

在【mysqld】下添加  socket =/usr/local/mysql/data/mysql/mysql.sock 

然后重启mysql 服务 

service msyql restart

2）连接时指定 socket目录

mysql -uroot -p123456 --socket='/usr/local/mysql/data/mysql/mysql.sock'

3）通过mysql.sockSet up soft connection in implementsocket连接

ln -s /usr/local/mysql/data/mysql/mysql.sock /var/lib/mysql/mysql.sock

Will I set 的socket文件位置,在/var/lib/mysqlPlaced under a,以供读取

结果如图：

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