Previous | Next

[zzz]

I have data in a table.

I get it to show based on a variable, something like:

...("SELECT pageNumber, capter  FROM t1 WHERE book_id = '$bID' ");

I would like to add PREVIOUS | NEXT links. I have a few blurry areas though, where I need some help.

First, the page numbers stored in a table could be in random order. So I guess I need to ORDER BY pageNumber first, right?

Then, What if I am on the first chapter -- I need to knwo that and hide PREVIOUS link. Same goes for NEXT if i'm on the last chapter...

:bemused:

[herve]

The idea : you only "print" a previous link if you aren't on the first page and
you don't print a next link if you are on the last page. That way you don't have
something to "hide".

if (I'm not on page 1)
{
    print link on page N-1
}

if (I'm not on page X)
{
   print link on page N+1
}

Where X = max page number

and N = current page I'm on.

[Merve]

First, I would read all the chapter numbers into an array. Then, for $chapter_number[0], you can hide PREVIOUS. For $chapter_number[sizeof($chapter_no)-1] you can hide the NEXT link.

[zzz]

How do I read all the chapter numbers into an array? And then how to I build the links.

Kinda at a loss still...

Something like this:

$chapter_number = array();

...("SELECT pageNumber, chapter  FROM t1 WHERE book_id = '$bID' "); 

foreach ($chapter_number as $chapter_no => $chapter)
{
   ...
}

Arrays always confuse me...

[herve]

Something like this :

myscript.php :

<?PHP

$db = mysql_connect("localhost", "mysql_user", "mysql_password");
mysql_select_db("database", $db);

if (isset($_REQUEST["current_page"])
{
	// Trying to get values coming from the URL

	$current_page    = $_REQUEST("current_page"];
	$current_chapter = $_REQUEST["current_chapter"];
}
else
{
	// Set default values

	$current_page = 1;
	$current_chapter = 1;    
}

// ***************************************************************

// Here code to display current page



// ***************************************************************
// Trying to get the previous page/chapter

if ($current_page != 1)
{
	// Simply decreasing the page number

	$previous_page = $current_page -1;
	$previous_chapter = $current_chapter;
}
else
{
	// We are on the first page of the current chapter

	if ($current_chapter != 1)
	{
		// we aren't on the first chapter, so we can go to the last page
		// of the previous chapter

		$previous_chapter = $current_chapter -1;

		$query = "SELECT MAX(pageNumber) as MaxPageNumber  FROM t1 WHERE (book_id = '$bID') AND (chapter = '$previous_chapter')";
		$result = mysql_query($query,$db);
		$myrow = mysql_fetch_array($result);

		$previous_page = $myrow["MaxPageNumber"];
}
else
{
	// Nothing here, we're on the first page, on the first chapter
	// so there's no "previous" link

	$previous_page= "";
	$previous_chapter = "";
}    	
}

if ($previous_page != "")
{
	print "<a href=\"myscript.php?current_page=$previous_page&$current_chapter=$previous_chapter\">Previous page</a>\n";
}

// ***************************************************************
// Trying to get the next page/chapter

$query = "SELECT MAX(pageNumber) as MaxPageNumber  FROM t1 WHERE (book_id = '$bID') AND (chapter = '$current_chapter')";
$result = mysql_query($query,$db);
$myrow = mysql_fetch_array($result);

$max_page_num = $myrow["MaxPageNumber"];

if ( ($current_page +1) <= $max_page_num)
{
	$next_page = $current_page +1;
	$next_chapter = $current_chapter;
}
else
{
	// We're already on the last page of the current chapter

	$query = "SELECT MAX(chapter) as MaxChapterNumber  FROM t1 WHERE book_id = '$bID'";
	$result = mysql_query($query,$db);
	$myrow = mysql_fetch_array($result);

	$max_chapter_num = $myrow["MaxChapterNumber"];

	if ( ($current_chapter +1) <= $max_chapter_num)
	{
		$next_chapter = $current_chapter +1;
		$next_page = 1; // Well I suppose each chapter begin at page 1 :) (otherwise a SELECT is needed)
	}
	else
	{
		// Nothing here, we're already at the last page of the last chapter
		// so there's no "next" link

		$next_chapter = "";
		$next_page = "";
	}

}

if ($next_page != "")
{
	print "<a href=\"myscript.php?current_page=$next_page&$current_chapter=$next_chapter\">Next page</a>\n";
}

?>

As I haven't test this code, there might be typos 🙂