Question

接下来我想要建立的是什么。获取我的所有菜单类别并显示它们，然后获取每个类别的所有子类别特别显示它。我希望你明白我的想法和说法。我迷失在代码中，现在不知道如何做到这一点。这是我的代码，希望你能帮助我。

这是表结构。

子类别表

| id | subcategory_name | id_category |

类别表

| id |类别|

id_category与类别表

中的id相关联

<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
      <ul class="nav navbar-nav navbar-left">
        <?php
          $pdo = connect();             
          $sql = "SELECT * FROM category";
          $query = $pdo->prepare($sql);
          $query->execute();
          $row = $query->fetchAll();      

          foreach ($row as $rs) { ?>

            <li class="dropdown"><a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-expanded="false"><?php echo $rs['category'] ?><span class="caret"></span></a>
              <ul class="dropdown-menu" role="menu">
                <?php
                $sql = "SELECT subcategory.subcategory_name, subcategory.id_category, category.id, category.category
                        FROM subcategory
                        INNER JOIN category
                        WHERE subcategory.id_category = category.category";
                $query = $pdo->prepare($sql);
                $query->execute();
                $subcat = $query->fetchAll();      

                foreach ($subcat as $sub) { ?>

                <li><a href="#"><?php echo $sub['subcategory_name'] ?></a></li>

                <?php } ?>

              </ul>  
            </li>

          <?php } ?>
      </ul>
      <ul class="nav navbar-nav navbar-right">
        <li><a href="includes/logout.php">Logout</a></li>
      </ul>
      </div><!-- /.navbar-collapse -->
    </div>

Answer 1

我认为你只是不理解INNER JOIN sql select语句。您必须声明第二个表与第一个表的关系：

SELECT column_list
FROM t1
INNER JOIN t2 ON join_condition1
WHERE where_conditions;

在您要将“subcategory.id_category = category.category”部分放入查询的位置加入条件。也许省略实际的WHERE子句？希望能帮助到你。看here

编辑：我建议指出重写完整的代码在一个查询中执行它。但是你的代码可以使用已捕获的变量和第一个sql查询快速简化：

<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
      <ul class="nav navbar-nav navbar-left">
        <?php
          $pdo = connect();             
          $sql = "SELECT * FROM category";
          $query = $pdo->prepare($sql);
          $query->execute();
          $row = $query->fetchAll(PDO::FETCH_ASSOC);      

          foreach ($row as $rs) { ?>

            <li class="dropdown"><a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-expanded="false"><?php echo $rs['category'] ?><span class="caret"></span></a>
              <ul class="dropdown-menu" role="menu">
                <?php
                $sql = "SELECT subcategory_name, id_category
                        FROM subcategory
                        WHERE id_category = '".$rs['id']."'";
                $query = $pdo->prepare($sql);
                $query->execute();
                $subcat = $query->fetchAll(PDO::FETCH_ASSOC);      

                foreach ($subcat as $sub) { ?>

                <li><a href="#"><?php echo $sub['subcategory_name'] ?></a></li>

                <?php } ?>

              </ul>  
            </li>

          <?php } ?>
      </ul>
      <ul class="nav navbar-nav navbar-right">
        <li><a href="includes/logout.php">Logout</a></li>
      </ul>
      </div><!-- /.navbar-collapse -->
    </div>

在获取的类别中获取子类别

1 个答案: