如果你brew install mysql 之后出现问题要卸载：

brew remove mysqlbrew cleanuplaunchctl unload -w ~/Library/LaunchAgents/com.mysql.mysqld.plistrm ~/Library/LaunchAgents/com.mysql.mysqld.plistsudo rm -rf /usr/local/var/mysql

然后重新开始

1. installed mysql with brew install mysql

2. ran the commands brew suggested:

   unset TMPDIR mysql_install_db --verbose --user=`whoami` --basedir="$(brew --prefix mysql)" --datadir=/usr/local/var/mysql --tmpdir=/tmp

3. Start mysql with mysql.server command, to be able to log on it

4. Used the alternate security script:

   /usr/local/Cellar/mysql/5.5.10/bin/mysql_secure_installation

5. Followed the launchctl section from the brew package script output

6. Boom.