Newbie question (maybe)

[JLerster]

I am a total newbie trying to teach myself how to code with PHP. Im not to savvy with coder lingo so I hope you can understand my qustion, since I don't quite know how to ask it.
A place were Im totaly stumped is how to get a script to only display 5 (or how erver many) listings
and then pervide a link to the next five and the five after that.
Example:
Pages (21): [1] 2 3 » ... Last »

I understand the basic query statement: $query = "SELECT *
FROM 'database' LIMIT 0, 5"; But how do I use hyperlinks to query the next five and so forth.

I know how to pass variables in URLs, thats not what Im getting at. Im talking more about how to get the script to turn
LIMIT 0,5 into LIMIT 5,5 and then on and on.

I'm not looking for a cut and paste soultion like here
http://www.phpbuilder.com/board/showthread.php?s=&threadid=10234923,
Im looking more for a simple explination on how it works so that I can understand it and code my own navigation.

Thanks.

[alanzhao]

It's not so practical to explain without examples, or codes, but I will make it simple and the rest of code you have to figure it out yourself.

Basically, there are few variables needed to manipulate the 'pagination'.

For example in a guestbook,

• $messagePerPage

• $totalMessage

• $totalPage

• $currentPage

• $messageOffset

let's see how we get those variables:

$messagePerPage
// predefined variable, let's say 20 message per page
$messagePerPage = 20;

$totalMessage
$totalMessage = $DB->query_first("SELECT count(id) as count FROM guestbook");

$totalPage
$totalPage = ($totalMessage == 0) ? 0 : ceil($totalMessage / $messagePerPage);

$currentPage
// GET variable, current page number
$currentPage = $_GET['page'];

$messageOffset
$messageOffset = $messagePerPage * $currentPage - $messagePerPage;

then, the query would be:

// for example: if the current page is 1, it would be LIMIT 0, 20, if page is two, it would be LIMIT 20, 20, an so on
$query = $DB->query("SELECT message FROM guestbook ORDER BY date DESC LIMIT $messageOffset, $messagePerPage");

You may wanna previous page and next page too🙂, here it is:

$previousPage
$previousPage = $currentPage - 1;

$nextPage
$nextPage = $currentPage + 1;

and for the navigation link it would be:

echo '<a href="index.php?page=$previousPage">Previous</a> ';
for ($i = 1; $i <= $totalPage; $i++)
{
    if ($currentPage == $i) {
        // highlight current page
        echo '<b>$i</b> ';
    } else {
        echo '<a href="index.php?page=$i">$i</a> ';
    }
}
echo ' <a href="index.php?page=$nextPage">Next</a>';

Write some code, you will understand better.
Hope it helps🙂

[JLerster]

Thanks, that helps some. One question though, were do you get $GET['page'] from? I see that is needed to make
$messageOffset, which is later needed for a LIMIT value. I tryed the script upto $messageOffset and tested both
$GET['page'] and $messageOffset, and $_GET['page'] came back NULL and $messageOffset printed out as -20.
Am I missing something?
Thanks again.

[alanzhao]

Ok, here is what I missed,

$currentPage
$currentPage = $_GET['page'];
if (!$currentPage) $currentPage = 1;

for $_GET, take a look at PHP's manual here

example of $_GET variable:

http://www.site.com/guestbook.php?page=1&message=10

then

$GET['page'] = 1
$GET['message'] = 10

:rolleyes:

[dinger]

In order to tell the script what page you are on you need to call the script like this:

http://www.yoursite.com/forum.php?page=1

for page 1

http://www.yoursite.com/forum.php?page=2

for page 2

etc

where page = x is $_GET['page']

Chris

[JLerster]

😃 Thanks much, I got it now.

[JLerster]

Ok, I understand it now fully. I used the above to make the code bellow. It will pull a listing of products out of a osCommerce database based on popularity 5 at a time. Thanks

<?php
include "func.php";

dbconnect();
dbselect(catalog);


$messagePerPage = 5; 

/* I have never seen a query quite like the one you did. Im new enough that I only know MySQL, and my knowledge
 of it is still minimal. Heres the MySQL eqivalint of your query (as I know it) */
$totalMessage = mysql_num_rows(
mysql_query("SELECT * FROM products")
); 

$totalPage = ($totalMessage == 0) ? 0 : ceil($totalMessage / $messagePerPage); 

$currentPage = $_GET['page'];
if (!$currentPage) $currentPage = 1;

$messageOffset = $messagePerPage * $currentPage - $messagePerPage; 

$previousPage = $currentPage - 1;

$nextPage = $currentPage + 1;

$sql = mysql_query("SELECT products_name, products_viewed, products_description, products_price, products_weight FROM products ORDER BY products_viewed DESC LIMIT $messageOffset, $messagePerPage") or die (mysql_error());

for($i = 0; $i < $messagePerPage; $i++){
for ($count = 1; $products = mysql_fetch_array($sql);++$count)
        {
	?>
<table width="65%" border="0" align="center">
  <tr> 
    <td width="40%" height="11"><font class="title">Product Name:&nbsp</font> 
      <font class="text1"><?php echo $products['products_name']; ?></font><br><font class="title">Times Viewed:&nbsp</font><font class="text1"><?php echo $products['products_viewed']; ?></font></td>
    <td width="30%">&nbsp;</td>
    <td width="30%"><img src="http://localhost:84/catalog/<?php echo $products['products_image']; ?>" width="100" height="80" align="right"></td>
  </tr>
  <tr>  

    <td height="4" colspan="3"><font class="text2"><?php echo $products['products_description']; ?></font></td>
  </tr>
  <tr> 
    <td height="5"><font class="title">Price:&nbsp</font><font class="text2"><?php echo $products['products_price']; ?></font><br><font class="title">weight(lb/s):&nbsp</font><font class="text2"><?php echo $products['products_weight']; ?></font></td>
    <td height="5" colspan="2">&nbsp;</td>
  </tr>
</table><hr>
<?php

}
}

if ($currentPage >= 2) { 
echo '<a href="index.php?page=' . $previousPage . '">Previous</a> ';
}

for ($i = 1; $i <= $totalPage; $i++)
{
    if ($currentPage == $i) {
        // highlight current page
        echo '<b>'. $i .'</b> ';
    } else {
        echo '<a href="index.php?page=' .$i .'">' . $i . '</a> ';
    }
}

if ($currentPage != $totalPage) { 
echo ' <a href="index.php?page=' . $nextPage . '">Next</a>';
}
?>