[PHP / MySQL] Prev & Next with images

[ic3d]

I created a script that fetches image urls out of a database and adds them on a page. Using the script i only want to display one image per page, the rest can be found using the forward and next buttons.

Everything seems to work but iam having problems with the forward and next buttons, they don't link all images and sometimes they dissapear. Does anyone know what iam doing wrong?

<?php $start=$_GET["start"];if(!isset($start)) $start = 0; ?> 

<?php 
include("database.inc.php"); 
$afbeeldingen = mysql_query("SELECT A_P_URL FROM afbeeldingen WHERE A_P_ID='8' LIMIT " . $start . ", 1"); 
$num_results = mysql_num_rows($afbeeldingen); 
if ($num_results == 0) { echo "<img src='images/geen.jpg' alt=''>"; } 
else {
$row = mysql_fetch_array($afbeeldingen); 
$urlafb = $row["A_P_URL"]; 
echo "<img src=\"".$urlafb."\" alt=\"\"><br>"; 
if($start > 0) { echo "<a href=\"" . $PHP_SELF . "?start=" . ($start-=1) . *"\">Previous</a><BR>\n"; } 
if($num_results > ($start++)) { echo "<a href=\"" . $PHP_SELF . "?start=" . ($start++) . *"\">Next</a><BR>\n"; } 
} 

 *
?> 

[sneakyimp]

There's a few things i would change:
if the query fails, throw an error message so you know
separate your code from your html output...keep information variables and only output html once you have gathered all of them
* $num_results will only be greater than $start when $start when $start is zero and an image is retrieved because your query has a LIMIT clause in it with the 2nd parameter of 1. You need to rethink your code a bit.

You are going to need two queries to determine if there is a NEXT button. There are two ways to do this:
1)
add 'SQL_CALC_FOUND_ROWS' after the word 'SELECT' in your query. this will cause SQL to calculate all the rows that would have been returned if there were no limit clause
run a second query: "SELECT FOUND_ROWS() as total_rows"
when you mysql_fetch_array the results of that query, total_rows will tell you how many total pics you have.

2) run your first query normally then run a query to simply count all the image records where A_P_ID = whatever without the limit clause

If the total number of rows > ($start+1) then you have a next button. otherwise you don't.