Why am I getting this type of error in this string:
$query="SELECT Name,Lastname FROM $_SESSION['SESS_MAIN_BASE'] s,
WHERE s.FK_ID_user={$id_user}
AND DATE(s.time) BETWEEN '".$d_year1."-".$d_month1."-".$d_day1."' AND '".$d_year2."-".$d_month2."-".$d_day2."'";
{}encapsulation notation.