selecting certain records

[c_pattle]

I have a page that select all the products from a mysql table and then prints them out to the screen.  However there are over 100 products so I want to be able to make it so it prints out 0-30, then when the user clicks next it displays 30-60 etc. 

 

What I've done so far is if you click next or previous it adds and takes away 30.  So if you click next it display 0-60 and if you click previous it display 0-30.  However how can I make it so that it doesn't always start at 0.  Hope this makes sense.  I've copied my code below. 

 

<a href="add_records.php?key19=30">previous</a>
<a href="add_records.php?key20=30">next</a>

<?php

//Fetching data from database and printing it out
$row_count = 1;
$row_max = 31;
if (isset($_GET['key20'])) {

$row_max +=30;
}

if (isset($_GET['key19'])) {
$_row_max -= 30;
}

while (( $row = mysql_fetch_array ( $rs ) ) and ($row_count < $row_max)) {
$table_row = "<tr><td>" . $row["id"] . "</td><td>" . $row["product_name"] . "</td><td>" . $row["price"] . "</td><td>" . $row["product_description"] . "</td><td>" . $row["department"] . "</td><td>" . $row["category"] . "</td><td>" . $row["size"] . "</td></tr>";
echo ($table_row);
$row_count ++;
}

?>

[premiso]

Take a look at this tutorial:

http://www.phpfreaks.com/tutorial/basic-pagination

 

It goes over the basics of pagination, which is what you are trying to do.