creating an offset

[Anon]

Hi,

Can anyone point me in the right direction. Im trying (in vain!) to create an offset for the below script which prints out thumbnail images. I have read Rod's articles on offsets and havent had any luck at all.

<?

if(@cid) {

   $result = @mysql_query("SELECT * FROM products, company WHERE products.cid=$cid AND company.cid=$cid");
   if (@$data = mysql_fetch_array($result)) 

     {
          do {

          $title = $data["title"];
          $thumbnail = $data["thumbnail"];
          $id = $data["id"];
          $info = $data["info"];

         echo "<a href=\"$PHP_SELF?id=$id&cid=$cid\"><img src=\"$thumbnail\" hspace=\"5\" border=\"1\" alt=\"$title\"></a>";

                } while ($data = mysql_fetch_array($result));
                }

 else {
 echo "</p>No items match your selection</p>.";
 }

}
?>

Any help would be greatly appreciated.
Thanks a lot,
dast

[quicknik]

hi,

what do you excatly mean by "offset"
only showing pict i to i+n ?
bye,

         niko

[theslinky]

Hi,

I assume you mean adding next/previous links?

Okay, do this:

First declare a variable like $offset which will be retrieved from a GET name=value pair:

$offset = $_GET['offset'];

Next decide on the # of entries (rows) you want to display and enter that number + 1 in another variable:

// For 20 rows, use 21
$numrows = 21;

The reason you want 21 is because you will be retrieving 21 rows from the database yet only displaying 20 of them. If the 21st row exists in the database, then you know that you can display an additional page since there are more entries.

Construct your query like this:

$SQ = "SELECT * FROM products, company WHERE products.cid=$cid AND company.cid=$cid LIMIT $offset,$numrows";

// print the "Previous" link if offset is NOT 0
if ($offset != 0) {
print "<a href=\"script.php?offset=\" . ($offset - $numrows) . "\">Previous</a>\n";
}

// start a counter so you ONLY PRINT $numrows rows
$count = 1;

// now print your rows for this page
$result = @("SELECT * FROM products, company WHERE products.cid=$cid AND company.cid=$cid");
if (@$data = mysql_fetch_array($result))

{
do {

$title = $data["title"];
$thumbnail = $data["thumbnail"];
$id = $data["id"];
$info = $data["info"];

echo "<a href=\"$PHP_SELF?id=$id&cid=$cid\"><img src=\"$thumbnail\" hspace=\"5\" border=\"1\" alt=\"$title\"></a>";

$count++;

} while ( ($data = mysql_fetch_array($result)) && ($count < 21) );
}

else {
echo "</p>No items match your selection</p>.";
}
}

// finally, see if there is a 21st row. If there IS, then print the NEXT link

if (@$data = mysql_fetch_array($result)) {
print "<a href=\"script.php?offset=" . ($offset + $numrows) . "\">Next</a>";
}

that's it! I haven't tested the code, so there may be syntax errors. If anyone notices any flaws, please post!

-sridhar

[Anon]

Thanks for you reply its greatly appreciated. I've tried to implement this script but am getting a Warning: Undefined variable: _GET error. This shows even if the offset variable is passed in the URL.

Any ideas?
Once again, thanks for the help.