To remove an instance of MySQL from your macOS or OSX installation you need to delete a number of files via the command line, but first ensure that you have database dumps of your databases and that then the database server is not running.

Back Up any needed databases

All of them

mysqldump --all-databases > all_databases_export.sql

Or individually

mysqldump database_name > database_exportname.sql

Stop the database server

>= MySQL 5.7

sudo launchctl unload -F /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

< MySQL 5.7

sudo /usr/local/mysql/support-files/mysql.server stop

Remove MySQL

sudo rm -rf /usr/local/mysq*

sudo rm  /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

sudo rm -rf /Library/StartupItems/MySQLCOM

sudo rm -rf /Library/PreferencePanes/My*

Edit /etc/hostconfig and remove the line MYSQLCOM=

rm -rf ~/Library/PreferencePanes/MySQL*

sudo rm -rf /Library/Receipts/mysql*

sudo rm -rf /Library/Receipts/MySQL*

sudo rm -rf /private/var/db/receipts/*mysql*

That’s it MySQL is now totally removed from your system

Brew install MySQL

• brew doctor and fix any errors
• brew update
• brew install mysql
• unset TMPDIR
• mysql_install_db --verbose --user=whoami --basedir="$(brew --prefix mysql)" --datadir=/usr/local/var/mysql --tmpdir=/tmp
• mysql.server start
• run the commands Brew suggests, add MySQL to launchctl so it automatically launches at startup

Autostart MySQL on boot

brew info mysql gives you the instructions for loading MySQL at startup, but here's all you need to do:

mkdir -p ~/Library/LaunchAgentscp `brew --prefix mysql`/*mysql*.plist ~/Library/LaunchAgents/launchctl load -w ~/Library/LaunchAgents/*mysql*.plist

mysql should now work and be running all the time as expected

reference：

（1）；

（2）；

（3）。