yum list installed mysqlrpm -qa | grep mysql以上两个查到的都删除掉，删除的是mysql的，不要删除其他程序的mysql插件，如果是升级MySQL，切记备份数据再删除，且安装前关闭mysql服务。

tar -xvzf mysql-5.7.26-linux-glibc2.12-x86_64.tar.gz
mv mysql-5.7.26-linux-glibc2.12-x86_64 /data0/mysql

groupadd mysql
useradd mysql -g mysql
cd /data0
chown -R mysql
chgrp -R mysql

[mysqld]
basedir=/data0/mysql
datadir=/data0/mysql/data
socket=/tmp/mysql.sock
user=mysql
character-set-server = utf8mb4
collation-server = utf8mb4_general_ci
init_connect='SET NAMES utf8mb4'
lower_case_table_names = 1
port = 3306
tmpdir  = /tmp

cd /data0/mysql
./bin/mysqld --initialize --user=mysql --basedir=/data0/mysql --datadir=/data0/mysql/data其中/data0/mysql/data/目录是新建的所属用户和组都是mysql5.7的初始使用的是mysqld --initialize
之前的版本使用的是mysql_install_db初始化后，会有几个Warning 最后一行会有个类似已下的输出内容，等于初始了一个root密码，需要用它登录：
2019-06-10T05:09:55.612961Z 1 [Note] A temporary password is generated for root@localhost: (rjLmqO-7rqB

cd /data0/mysql/support-files/
./mysql.server start

初始化时MySQL提供了一个密码，要是没有记录的话，
在/root/.mysql_secret文件中也有临时密码可以使用。cd /data0/mysql
./bin/mysql -uroot -p'临时密码'登录成功设置root密码：
set password=password('123456789');设置远程连接
GRANT ALL PRIVILEGES ON *.* TO root@'%' identified by '123456789';
flush privileges;

cp /data0/mysql/support-files/mysql.server /etc/init.d/mysqld此时就可以使用service命令：
service mysqld stop
service mysqld start添加开机启动的话：
chkconfig --add mysqld
chkconfig --list mysqldchkconfig mysqld on

ln -s /data0/mysql/bin/mysql /usr/bin/mysql这样就能全局使用
mysql -uroot -pxxx

MySQL升级导致的问题
[Err] 1055 - Expression #1 of ORDER BY clause is not in GROUP BY clause and contains nonaggregated column 'information_schema.PROFILING.SEQ' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

mysql> SHOW VARIABLES LIKE '%sql_mode%';+---------------+-------------------------------------------------------------------------------------------------------------------------------------------+
| Variable_name | Value                                                                                                                                     |
+---------------+-------------------------------------------------------------------------------------------------------------------------------------------+
| sql_mode      | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+---------------+-------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)看到ONLY_FULL_GROUP_BY这一项，这是5.7的新功能，和老版本兼容出现了问题。
解决：去掉它
select version(),
@@sql_mode;SET sql_mode=(SELECT REPLACE(@@sql_mode,'ONLY_FULL_GROUP_BY',''));mysql> SHOW VARIABLES LIKE '%sql_mode%';
+---------------+------------------------------------------------------------------------------------------------------------------------+
| Variable_name | Value                                                                                                                  |
+---------------+------------------------------------------------------------------------------------------------------------------------+
| sql_mode      | STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+---------------+------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)