Error establishing a database connection

After and updating MySQL to v5.6 I have been receiving multiple instances of “Error establishing a database connection”, I have used the optimize and repair tools in phpMyAdmin and added, ‘define( ‘WP_ALLOW_REPAIR’, true );
‘ to my wp-config.php file and I am still getting the error. At first there was a disk space issue which has been taken care of but ever since the update I have been having issues with the database. Any suggestions of how to resolve this issue. I have very little experience working with databases.