Set Global Variables (MySQL)
Knowledge of global variables principally allows the alteration of various setings that would otherwise require a restart of mysql.
To list current variables:
show variables;
To list current variables with 'slow' anywhere in the name:
show variables like '%slow%';
To set a global variables, this example to increase max_connect_errors:
set global max_connect_errors = 20;
Query OK, 0 rows affected (0.00 sec)