chained select ajax call only only works if value is a numbers

Question

我有以下ajax代碼片段，鏈接2個選擇框，並使用mysql表中找到的值動態填充。

如果callType列是一個數字值，比如我的數據列SPG_CallType中找到的數值，那麼這很有用。當我改變這個使用聯繫字母的字段時，它會打破它。我假設這是因爲代碼僅適用於數值？如何更新片段的這一部分以接受alpha或數字？

if (isset($_GET['key'])) { 
    $key = $_GET['key']; 
    switch ($key) { 
     case 'callTypeSelect': 
      $select = new SelectBox('Repair Type?','Choose a category'); 
      $res = mysql_query('SELECT DISTINCT SPG_CallType FROM ' . DB_TABLE . ' ORDER BY SPG_CallType ASC'); 
      $callTypes = array(); 
      for ($i = 0; list($callType) = mysql_fetch_row($res); $i++) { 
       $callTypes[] = $callType; 
       $select->addItem($callType, 'brandSelect-' . $callType); 
      } 
      header('Content-type: application/json'); 
      echo $select->toJSON(); 
      break; 
     default: 
      if (strpos($key, 'brandSelect-') === 0) { 
       $callType = str_replace('brandSelect-', '', $key); 
       $resBrands = mysql_query('SELECT SPG_Brand FROM ' . DB_TABLE 
        . ' WHERE SPG_CallType = ' . mysql_real_escape_string($callType) . ' ORDER BY SPG_Brand ASC'); 
       $select = new SelectBox('Choose a Manufacturer', 'Pick a brand'); 
       for ($i = 0; list($brand) = mysql_fetch_row($resBrands); $i++) { 
        $select->addItem($brand, 'result-' . $brand . '-' . $callType); 
       } 
       header('Content-type: application/json'); 
       echo $select->toJSON(); 

Answer 1

@ roryok回答了這個問題，但沒有辦法給予評論，但評論？

$select->addItem('\'' . $callType . '\'', 'brandSelect-' . $callType);