$lastBooking=$this->db->query("SELECT booking.id,review.rate FROM booking LEFT JOIN review ON review.event_id = booking.event_id WHERE booking.customer_id = ".$user_id." ORDER BY booking.id DESC LIMIT 1")->row_array();
$sql="SELECT booking.id,review.rate
FROM booking
LEFT JOIN review ON review.event_id=booking.event_id AND
review.customer_id=booking.customer_id
WHERE booking.customer_id = ".$user_id." AND booking.status='2'