php/mysql 动态菜单答案

【问题标题】：php/mysql dynamic menuphp/mysql 动态菜单
【发布时间】：2014-03-26 00:25:41
【问题描述】：

我有一个现有的下拉菜单，我正在尝试将其转换为 PHP/MySQL 以允许客户端编辑菜单项。这是结构：

首页-index.php
关于我们-#
-about.php
-annualreport.php
-awards.php
服务-#
-services.php
-loans.php

等等。我正在使用的查询是：

select distinct mainlinks.id as daddyid, mainlinks.title as daddytitle, mainlinks.urlink as daddyurl, babylinks.id as babyid, babylinks.title as babytitle, babylinks.urlink as babyurl from mainlinks, babylinks where mainlinks.id = babylinks.parentid order by mainlinks.listorder";

结果显示如下代码：

$result = mysql_query($query) or die(mysql_error());
// keep track of previous maincategory
$previous_maincategory = NULL;

while ($row = mysql_fetch_assoc($result))
{

        // if maincategory has changed from previouscategory then display it
        if ($previous_maincategory != $row['daddytitle']) 
        {
                echo "<strong><h2>" . strtoupper($row['daddytitle']) . "</h2></strong>";
        }

        echo '<a onclick="return confirmSubmit()" class="inside" href="deletesubcategory.php?id=';
        echo $row['babyid'];
        echo '">';
        echo $row['babytitle'];
        echo "</a>";
        echo "<br/>";

        // record what the previous category was
        $previous_maincategory = $row['daddytitle'];
}

它只显示具有子元素的项目，而不显示没有子元素的父项目。有任何想法吗？我猜问题出在查询 where 子句上，但我不知道如何获取我需要的东西。谢谢。

【问题讨论】：

标签： php mysql drop-down-menu

【解决方案1】：

你必须使用LEFT JOIN来获取没有孩子的物品，试试

select distinct mainlinks.id as daddyid, mainlinks.title as daddytitle, mainlinks.urlink as daddyurl, babylinks.id as babyid, babylinks.title as babytitle, babylinks.urlink as babyurl 
from mainlinks 
  LEFT JOIN babylinks ON mainlinks.id = babylinks.parentid
order by mainlinks.listorder;

【讨论】：

【解决方案2】：

您的查询仅抓取项目where mainlinks.id = babylinks.parentid，这意味着它将忽略不存在该关系的项目。

试试这个：

SELECT DISTINCT mainlinks.id as daddyid, mainlinks.title as daddytitle, mainlinks.urlink as daddyurl, babylinks.id as babyid, babylinks.title as babytitle, babylinks.urlink as babyurl FROM mainlinks LEFT JOIN babylinks ON mainlinks.id = babylinks.parentid ORDER BY mainlinks.listorder

使用LEFT JOIN 将告诉您的查询拉取所有主链接，无论它们是否有子链接，但只拉取有父链接的子链接。

【讨论】：

完美运行。谢谢大家。