Mine

/**
 * hook_db_rewrite_sql
 */
function parametric_db_rewrite_sql($query, $primary_table, $primary_field, $args) {
//  if ($primary_field == 'nid' && $query = 'views_build_view') {
    $fl_min = $_SESSION['fl_min'];
    $fl_max = $_SESSION['fl_max'];
    $return['where']  = 'field_fl_min_value >= ' .$fl_min. ' AND ';
    $return['where'] .= 'field_fl_min_value <= ' .$fl_max;
    return $return;
//  }
}