public function listen(Closure $callback)
    {
        if (isset($this->events)) {
            $this->events->listen(Events\QueryExecuted::class, $callback);
        }
    }
public function listen(Closure $callback)
    {
        if (isset($this->events)) {
            $this->events->listen(Events\QueryExecuted::class, $callback);
        }
    }
public function listen ( Closure $ callback ) { if ( isset ( $ this -> events ) ) { $ this -> events -> listen ( Events \ QueryExecuted :: class , $ callback ) ; } }
Register a database query listener with the connection.

@param  \Closure  $callback
@return void
Register a database query listener with the connection .