PHP - Using Foreach With Mysql (i Think)

Hi, I am new to php, mysql and have made some progress, but recently ran into a wall. I hope someone can help me. I am building a simple links script that has categories and a list of links with website name, url and a brief description.  I have two tables-categories and links.

I have gotten the back end finished and can add, edit and delete links and categories. The problem is in the front end.  I have the script set up so that when I click on a category name a page is dynamically created using ?id=idnumber.  and the category name is echoed on the page. But I can't seem to find the solution I need to get the links that have a matching category name to display. I have tried using JOIN, LEFT JOIN, INNER JOIN, and RIGHT JOIN and get the same result, ALL the links in the links table are displayed.

I think I need to create a new array and use the foreach loop to accomplish this, but I am not sure. Nor am I sure how to use the foreach even though I have read several tutorials on it. 

Here is the code I have so far. Any help would be appreciated. Thanks in advance.

Code: [Select]
<? include "db.php" ?>
<?php
$id = intval($_GET['id']); // force user input to an int
if(!empty($id)) // if the user input is not empty or 0
{
$query = "SELECT * FROM categories WHERE id =  $id  LIMIT 1"; // attempt to select the row for the given id
$result = mysql_query($query) or die(mysql_error());

if(mysql_num_rows($result) > 0) // if the categorie was found
{
$row = mysql_fetch_assoc($result); // fetch the resultset to an array called $row

echo $row['categories']; // echo the categories field from the row
// etc.
}
else
{
die('Error: Bad ID'); // the categories was not found
}
}
else
{
die('Error: Bad ID'); // the id given was not valid
}
mysql_close();
?>
<? include "db.php" ?>
<?php
$sql="SELECT * FROM links,categories ORDER BY links.categories LIMIT 10";
$result=mysql_query($sql);

?>
<table width="80%" align="center" border="0" cellspacing="1" cellpadding="0">
<tr>
<td>
<table width="100%" border="1" cellspacing="0" cellpadding="3">
<tr>
<td colspan="3"><strong>List data from mysql </strong> </td>
</tr>

<tr>
<td align="center"><strong>Name</strong></td>
<td align="center"><strong>URL</strong></td>
<td align="center"><strong>Content</strong></td>
</tr>
<?php
while($rows=mysql_fetch_array($result)){
?>
<tr>
<td><? echo $rows['name']; ?></td>
<td><a href="<? echo $rows['url']; ?>"><? echo $rows['url']; ?></a></td>
<td><? echo $rows['content']; ?></td>
</tr>
<?php
}
?>
</table>
</td>
</tr>
</table>
<?php
mysql_close();
?>