Reinstall mysql using brew:

Remove mysql installation and cleanup using brew:

brew remove mysql

brew cleanup

unload homebrew.mxcl.mysql.plist if already loaded and remove it:

launchctl unload -w ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist

rm ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist

Install mysql using brew:

brew install mysql

Set up databases to run AS YOUR USER ACCOUNT with:

unset TMPDIR

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

Start the mysql server:

mysql.server start

Set the root password

/usr/local/Cellar/mysql/5.5.19/bin/mysqladmin -u root password 'new-password'

Setting the root password ensures that nobody can log into the MySQL

root user without the proper authorisation.

Alternatively you can run following command and follow the steps:

/usr/local/Cellar/mysql/5.5.19/bin/mysql_secure_installation

which will also give you the option of removing the test databases and anonymous user created by default.  This is strongly recommended for production servers. See the manual for more instructions.

To launch on startup:

* if this is your first install:

    mkdir -p ~/Library/LaunchAgents

    cp /usr/local/Cellar/mysql/5.5.19/homebrew.mxcl.mysql.plist ~/Library/LaunchAgents/

    launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist

* if this is an upgrade and you already have the homebrew.mxcl.mysql.plist loaded:

    launchctl unload -w ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist

    cp /usr/local/Cellar/mysql/5.5.19/homebrew.mxcl.mysql.plist ~/Library/LaunchAgents/

    launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist

You may also need to edit the plist to use the correct "UserName".