Calendar: Validation & Query String

Validate Input and Set Optional Query String Segment

if ( empty($Form->CategoryID)  OR  !is_array($Form->CategoryID) ) {
    $Form->CategoryID = array();
    $Category = '';
} else {
    foreach ($Form->CategoryID AS $Key => $Value) {
        if ( !is_string($Value)  OR  !preg_match('/^\d{1,5}$/', $Value) ) {
            unset($Form->CategoryID[$Key]);
        }
    }
    $Category = ' AND CategoryID IN ('
            . implode(',', $Form->CategoryID) . ')';
}

Set Query String

$SQL->SQLQueryString = "SELECT {$Layout->BSYear}_Calendar.CalendarID,
 CategoryIDCSV, Title,
 LOWER(TIME_FORMAT(TimeStart, '%l:%i %p')) AS TimeStartStr
 FROM {$Layout->BSYear}_Calendar
 LEFT JOIN {$Layout->BSYear}_CalendarCategories
  ON ({$Layout->BSYear}_CalendarCategories.CalendarID
  = {$Layout->BSYear}_Calendar.CalendarID)
 WHERE ( (DateStart BETWEEN '$Form->From' AND '$Form->To')
  $Category
 GROUP BY CalendarID";