Question

I have two tables called categories and topics.

categories has columns category_id and category_title. topics has columns topic_id, topic_title, and category_id.

I currently display the columns like so:

$result = mysqli_query($db_server, 'SELECT c.category_title, t.topic_title FROM categories c JOIN topics t on c.category_id = t.category_id');

while ($row = mysqli_fetch_array($result))
{
$category_title[] = $row['category_title'];
$topic_title[] = $row['topic_title'];
}

<?php

foreach ($category_title as $category_title): 

echo htmlspecialchars($category_title, ENT_QUOTES, 'UTF-8');?><br />

<?php endforeach; ?>

<?php

foreach ($topic_title as $topic_title): 

echo htmlspecialchars($topic_title, ENT_QUOTES, 'UTF-8');?><br />

<?php endforeach; ?>

This will display as:

Category 1
Category 1
Category 2

Topic 1
Topic 2
Topic 3

Topic 1 and 2 are assigned to Category 1, while Topic 3 is assign to Category 2.

How can I have Category display once if there are multiple topics assign to it, such as:

Category 1
Category 2

Topic 1
Topic 2
Topic 3

Please no classes and objects examples. I’m not learning that yet.

Answer 1

You can run query two time first for category then run new query to selected topic according to category as below:

<?php
$result = mysqli_query($db_server, 'SELECT c.category_id,c.category_title FROM categories as c');
    $recordArray=array();
    while ($row = mysqli_fetch_array($result))
    {
    $category_id = $row['category_id'];
    $recordArray[$category_id] = $row['category_title'];
    //Query For Topic
    $getTopic = mysqli_query($db_server, "SELECT t.topic_title FROM topics as t WHERE t.category_id='".$category_id."'");
    while ($getRow = mysqli_fetch_array($getTopic))
    {
        $recordArray[$category_id]['topic'][] = $getRow['topic_title']; 
    }

}
print"<pre>";
print_r($recordArray);
?>