Fetch subcategory in fetched category - php

Question

What i am trying to build is next. Fetch all my menu categories and display them, then fetch all subcategories for each category special all display it also. I hope you understand what i want and saying. I got lost in code and don't now how to do this. Here is my code, hope you can help me.
Here is table structure.
subcategory table
| id | subcategory_name | id_category |
category table
| id | category |
id_category is connected with id in category table
<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"><?php echo $rs['category'] ?><span class="caret"></span>
<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><?php echo $sub['subcategory_name'] ?></li>
<?php } ?>
</ul>
</li>
<?php } ?>
</ul>
<ul class="nav navbar-nav navbar-right">
<li>Logout</li>
</ul>
</div><!-- /.navbar-collapse -->
</div>

Answer 1

I think you just didn't understand the INNER JOIN sql select statement. You have to declare the relation of the second table with the first one:
SELECT column_list
FROM t1
INNER JOIN t2 ON join_condition1
WHERE where_conditions;
Join condition in where you want to put the "subcategory.id_category = category.category" part of your query. Maybe leave out the actual WHERE clause?
Hope it helps.
Look here
Edit:
WHat I was proposing pointed to rewrite the complete code to do it in one query. But your code could be simplified like this quickly using the already captured variable with the first sql query:
<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"><?php echo $rs['category'] ?><span class="caret"></span>
<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><?php echo $sub['subcategory_name'] ?></li>
<?php } ?>
</ul>
</li>
<?php } ?>
</ul>
<ul class="nav navbar-nav navbar-right">
<li>Logout</li>
</ul>
</div><!-- /.navbar-collapse -->
</div>