public static function update(Category $oCategory)
 {
     $sName = addslashes($oCategory->getName());
     $sDescription = addslashes($oCategory->getDescription());
     $sImage = addslashes($oCategory->getImage());
     //  get product id
     $iCategoryId = $oCategory->getId();
     $sQuery = "update category ";
     $sQuery .= "set name='{$sName}',description='{$sDescription}',image='{$sImage}'";
     $sQuery .= " where id = {$iCategoryId}";
     $bSuccess = DBOperation::exec($sQuery);
     if (!$bSuccess) {
         return false;
     }
     return true;
 }