逻辑上选择类别和子类别(php,joomla,javascript,ajax)

您好我已经为joomla安装了jbusinessdirectory组件,并且我在tmpl/default.php文件中有名为mod_jbusinessdirectory的模块(这是商业列表的搜索模块)我有选择代码:(见下文)

get('showCategories')){ ?>
    

        

        
    category
    
    get('categorySearch')==$category->id && $preserve?" selected ":"" ?> >name?>
    subcategories)){?>
    subcategories as $subCat){?>
    get('categorySearch')==$subCat->id && $preserve?" selected ":"" ?> >-- name?>
    
      
      
    
    
 

从这段代码我得到类别和子类别,如下所示:

主要类别1

子类别1子类别2子类别3

主要类别2

子类别1子类别2子类别3

截图在这里:类别和子类别截图

在helper.php中,我有从数据库中获取类别和子类别的函数

static function getMainCategories(){
    $db = JFactory::getDBO();
    $query = ' SELECT * FROM #__jbusinessdirectory_categories where parent_id=1 and published=1  order by name';
    $db->setQuery($query);
    return $db->loadObjectList();
}

static function getSubCategories(){
    $db = JFactory::getDBO();
    $query = ' SELECT c.* FROM #__jbusinessdirectory_categories c
               inner join  #__jbusinessdirectory_categories  cc  on c.parent_id = cc.id  where c.parent_id!=1  and cc.parent_id = 1 and c.published=1
               order by c.name';
    $db->setQuery($query,0,1000);
    $result = $db->loadObjectList();

    return $result;
}

最后在modjbusinesdirectory.php文件中我有这样的PHP:

if($params->get('showCategories')){
    $categories =  modJBusinessDirectoryHelper::getMainCategories();
    if($params->get('showSubCategories')){
        $subCategories = modJBusinessDirectoryHelper::getSubCategories();
        foreach($categories as $category){
            foreach($subCategories as $subCat){
                if($category->id == $subCat->parent_id){
                    if(!isset($category->subcategories)){
                        $category->subcategories = array();
                    }
                    $category->subcategories[] = $subCat;
                }
            }
        }
    }
}

类别和子类别表结构截图 在这里

我的问题是:如何制作两个选择查询而不是一个.在第一个查询中我得到主要类别,在第二个查询中我得到子类别(例如:如果我从第一个查询中选择主要类别书籍,在第二个查询中我选择子类别,它必须仅显示具有子类别的书籍儿童书籍).