Syntax:
SET variable_assignment [, variable_assignment] ...

variable_assignment:
      user_var_name = expr
    | [GLOBAL | SESSION] system_var_name = expr
    | [@@global. | @@session. | @@]system_var_name = expr

The SET statement assigns values to different types of variables that
affect the operation of the server or your client.

URL: http://dev.mysql.com/doc/refman/5.7/en/set-statement.html

