僅顯示列表中的第一個結果

Question

我正在使用Zen Cart，目前正在爲電子商務網站構建菜單。我已經設法弄清楚如何調用所有類別，但客戶只需要顯示前四個類別。目前有超過20個類別，我只需要前4名顯示在列表中。我不確定最好，最簡單的方法來做到這一點。

有沒有辦法來調用列表

例子：

<ul> 
    <li>Menu One</li> 
    <li>Menu Two 
     <ul> 
     <li>Submenu One</li> 
     <li>Submenu Two</li> 
     <li>Submenu Three</li> 
     </ul> 
    </li> 
    <li>Menu Three</li> 
    <li>Menu Four</li> 
    <li>Menu Five</li> 
    <li>ect...</li> 
</ul> 

，然後只顯示

<ul> 
    <li>Menu One</li> 
    <li>Menu Two 
     <ul> 
     <li>Submenu One</li> 
     <li>Submenu Two</li> 
     <li>Submenu Three</li> 
     </ul> 
    </li> 
    <li>Menu Three</li> 
    <li>Menu Four</li> 
</ul> 

我希望這是一個簡單的解決方案！

謝謝！

Answer 1

根據您的回覆，您的查詢應該是：

// Categories 
$lid = (int) $_SESSION['languages_id']; 
$sql = "SELECT c.categories_id, cd.categories_name, c.parent_id " 
    . "FROM " . TABLE_CATEGORIES . " c, " 
    . TABLE_CATEGORIES_DESCRIPTION . " cd " 
    . "WHERE c.categories_id = cd.categories_id and c.categories_status = 1 " 
    . "AND cd.language_id = '{$lid}' " 
    . "ORDER BY c.parent_id, c.sort_order, cd.categories_name " 
    . "LIMIT 4"; 
$categories = $db->Execute($sql); 

// Subcategories of the above 
$lid = (int) $_SESSION['languages_id']; 
$sql = "SELECT c.categories_id, cd.categories_name, c.parent_id " 
    . "FROM " . TABLE_CATEGORIES . " c, " 
    . TABLE_CATEGORIES_DESCRIPTION . " cd " 
    . "WHERE c.categories_id IN (" 
    .  "SELECT c.categories_id " 
    .  "FROM " . TABLE_CATEGORIES . " c, " 
    .  TABLE_CATEGORIES_DESCRIPTION . " cd " 
    .  "WHERE c.categories_id = cd.categories_id and c.categories_status = 1 " 
    .  "AND cd.language_id = '{$lid}' " 
    .  "ORDER BY c.parent_id, c.sort_order, cd.categories_name " 
    .  "LIMIT 4" 
    . "); 
$subcategories = $db->Execute($sql); 

我不知道你的數據庫的結構，但你可以使用上面做了2步方法。第一個是獲得前四個類別。第二個查詢是獲得這4個類別的子類別。

我不太贊成子查詢 - 我儘可能避免它們，所以在我看來，這不是一個非常有效的解決方案。你可以有效地從那裏穿過第一個查詢並獲得IDS像這樣：

// Categories 
$lid = (int) $_SESSION['languages_id']; 
$sql = "SELECT c.categories_id, cd.categories_name, c.parent_id " 
    . "FROM " . TABLE_CATEGORIES . " c, " 
    . TABLE_CATEGORIES_DESCRIPTION . " cd " 
    . "WHERE c.categories_id = cd.categories_id and c.categories_status = 1 " 
    . "AND cd.language_id = '{$lid}' " 
    . "ORDER BY c.parent_id, c.sort_order, cd.categories_name " 
    . "LIMIT 4"; 
$categories = $db->Execute($sql); 

// Loop through the $categories and get the ids 
$category_ids = array(); 
foreach ($categories as $category) 
{ 
    $category_ids[] = $caregory->categories_id; 
} 
// Subcategories of the above 
$lid = (int) $_SESSION['languages_id']; 
$sql = "SELECT c.categories_id, cd.categories_name, c.parent_id " 
    . "FROM " . TABLE_CATEGORIES . " c, " 
    . TABLE_CATEGORIES_DESCRIPTION . " cd " 
    . "WHERE c.categories_id IN (" . implode(",", $category_ids) . ")"; 
$subcategories = $db->Execute($sql); 

以上在我看來比子查詢好得多。

HTH

貸Lion