ubuntu16.04彻底卸载mysql并且重新安装mysql

首先删除mysql:

sudo apt-get remove mysql-*
dpkg -l |grep ^rc|awk '{print $2}' |sudo xargs dpkg -P

清理完毕：

dpkg: error: --purge needs at least one package name argument

Type dpkg --help for help about installing and deinstalling packages [*];
Use 'apt' or 'aptitude' for user-friendly package management;
Type dpkg -Dhelp for a list of dpkg debug flag values;
Type dpkg --force-help for a list of forcing options;
Type dpkg-deb --help for help about manipulating *.deb files;

Options marked [*] produce a lot of output - pipe it through 'less' or 'more' !

然后安装mysql.

可以直接默认安装：

sudo apt-get install mysql-client mysql-server

因为Ubuntu是16.04的，所以会默认安装5.7版本。

如果要安装5.6（因为5.7版本据说经常出错），按以下步骤：

sudo add-apt-repository 'deb http://archive.ubuntu.com/ubuntu trusty universe'  //增加旧的repo

sudo apt-get update  //更新源

sudo apt-cache search mysql | grep 5.6   //查看软件源里时候有mysql 5.6 可供安装

//查看结果
percona-server-server-5.6 - Percona Server database server binaries
percona-server-test-5.6 - Percona Server database test suite
percona-xtradb-cluster-server-5.6 - Percona XtraDB Cluster database server binaries
mysql-client-5.6 - MySQL database client binaries
mysql-client-core-5.6 - MySQL database core client binaries
mysql-common-5.6 - MySQL 5.6 specific common files, e.g. /etc/mysql/conf.d/my-5.6.cnf
mysql-server-5.6 - MySQL database server binaries and system database setup
mysql-server-core-5.6 - MySQL database server binaries
mysql-source-5.6 - MySQL source
mysql-testsuite-5.6 - MySQL 5.6 testsuite

sudo apt-get install mysql-server-5.6 mysql-client-5.6  //安装

 安装完成后查看mysql状态：

sudo service mysql status

一般安装完成之后都是会自动运行的。
如果没有运行你可以

sudo service mysql start

运行它。

error：当时状态属于inactive(dead)，然后我运行，结果报错：

 Job for mysqld.service failed because the control process exited with error code. See "systemctl status mysqld.service" and "journalctl -xe" for details.

解决：

[root@izx5uaa5mz0yf0z ~]# ls -ld /var/run/mysqld/
drwxr-xr-x 2 mysql mysql 60 1月  22 21:48 /var/run/mysqld/
[root@izx5uaa5mz0yf0z ~]# mkdir -p /var/run/mysqld
[root@izx5uaa5mz0yf0z ~]# ls -ld /var/run/mysqld/
drwxr-xr-x 2 mysql mysql 60 1月  22 21:48 /var/run/mysqld/
[root@izx5uaa5mz0yf0z ~]#sudo chown mysql.mysql /var/run/mysqld/
[root@izx5uaa5mz0yf0z ~]# sudo /etc/init.d/mysql start
[ ok ] Starting mysql (via systemctl): mysql.service.

 成功：