prev next link headache

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June 25th, 2002, 09:14 AM

Anonymous

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prev next link headache

Hi,
I am trying to do a prev next link using php. But i seem to be having a problem and i dont know where went wrong. It would be nice if you guys could comment about it.

Please bear with the code below cause i am very new at this.

TIA
Braendan

<?php

//
// Connects to sql server and logs in with username and password and select the required database
//

$connect=@mysql_connect("localhost","username","password") or die ("couldnt connect to sql server");

$db= @mysql_select_db("test") or die ("couldnt select database");

//
// This is where you choose the ammount you want to display in one page
//

$per_page = 5;

//
// Selects all of the data from database
//

$sql_text = ("SELECT * from pdf ORDER BY id DESC");

//
// Sets page number, if no page is specified, it will create page 1
//

if(!$page) {
$page = 1;
}
$prev_page = $page - 10;
$next_page = $page + 10;

$query = @mysql_query($sql_text);

// Sets up specified page

$page_start = ($per_page * $page) - $per_page;

$num_rows = @mysql_num_rows($query);

if($num_rows <= $per_page) {
$num_pages = 1;
}
else if (($num_rows % $per_page) == 0) {
$num_pages = ($num_rows / $per_page);
}
else {
$num_pages = ($num_rows / $per_page) + 1;
}
$num_pages = (int) $num_pages;

if (($page > $num_pages) || ($page < 0)) {
error("You have specified an invalid page number");
}
$sql_text = $sql_text . " LIMIT $page_start, $per_page";
$query = mysql_query($sql_text);

?>

<title>Output here</title>
 There are currently
<?php echo "$num_rows"; ?>  files in this section

<?php

while ($result = mysql_fetch_array($query)) {

echo "Document ID:".$result['id']." n";
echo "Title:".$result['title']." n";
echo "File:<a href="$file" target="_blank">".$result['file']."</a>n";

}

// This displays the "Previous" link

if ($prev_page) {
echo "<a href="$PHP_SELF?page=$prev_page">< Prev</a>";
}

// This loops the Pages and displays individual links =

for ($i = 1; $i <= $num_pages; $i++) {
if ($i != $page) {
echo " <a href=$PHP_SELF?page=$i>$i</a>";
} else {
echo " $i ";
}
}

// This displays the "Next" link.

if ($page != $num_pages) {
echo " |<a href="$PHP_SELF?page=$next_page"> Next ></a>" ;
}

?>

</body>
</html>

June 25th, 2002, 09:19 AM

Anonymous

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Join Date: Apr 2007

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RE: prev next link headache

$prev_page = $page - 1;
$next_page = $page + 1;

Hi sorry bout that please ommit the prev post on these to line with the new one above.

TIA,
Braendan

June 25th, 2002, 10:56 AM

EvilivE

Join Date: Apr 2007

Location: Milwaukee, WI USA

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RE: prev next link headache

Looks fine, what are the error msgs that your getting?

June 26th, 2002, 01:40 AM

russ

Join Date: Apr 2007

Location: London, UK

Posts: 129

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RE: prev next link headache

Hey, I'm getting prev and next links trouble too, basicly its not showing the next 10 in the row, Its probably something so simple, but I just can't see the problem

php Code:

Original - php Code

 
if($_GET['action'] == 'sortby') 
{
 
$result = mysql_query("select * FROM guitardb WHERE band LIKE '".strtoupper($_GET['char'])."%' ORDER BY band ASC LIMIT 10",$db); 
 
while($myrow = mysql_fetch_array($result))
 
{
echo "<br>" . $myrow['band'] . " - <a href=?action=view&id=" .$myrow[id]. " class=link>" .$myrow['song']. "</a>";
}
 
if(!isset($start)) $start = 0;
 
$query = ("SELECT * FROM guitardb LIMIT " . $start . ", 10");
 
$result = mysql_query($query); 
 
 
$query = "SELECT count(*) as count FROM guitardb"; 
$result = mysql_query($query);
$row = mysql_fetch_array($result);
$numrows = $row['count'];
 
echo("<p>");
 
if($start > 0) 
   echo("<a href=?action=sortby&char=" .strtoupper($_GET['char']). "&start=" . ($start - 10) . " class=link>Previous</a> ");
 
if($numrows > ($start + 10)) 
   echo("<a href=?action=sortby&char=" .strtoupper($_GET['char']). "&start=" . ($start + 10) . " class=link>Next</a>");
 
 
}
 
 
 
 
 
elseif($_GET['action'] == 'view')
{
 
$result = mysql_query("SELECT * FROM guitardb WHERE id=$id",$db); 
 
$myrow = mysql_fetch_array($result); 
 
{
echo( "<pre>"  );
 
echo( $myrow['tab'] );
 
echo( "</pre>" );
}
 
}
 
 
 
 
 
 
 
 
 
else
 
{
 
$result = mysql_query("SELECT * FROM guitardb ORDER BY id desc LIMIT 50",$db); 
 
while($myrow = mysql_fetch_array($result))
 
{
 
echo "<br>" . $myrow['band'] . " - <a href=?action=view&id=" .$myrow[id]. " class=link>" .$myrow['song']. "</a>";
 
}
 
}

June 26th, 2002, 03:37 AM

EvilivE

Join Date: Apr 2007

Location: Milwaukee, WI USA

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RE: prev next link headache

Russ -> it looks like the problem is in your if($_GET['action'] == 'sortby') statments. The first thing I noticed is that you never do anything with:

php Code:

Original - php Code
$query = ("SELECT * FROM guitardb LIMIT " . $start . ", 10"); $result = mysql_query($query);

 
$query = ("SELECT * FROM guitardb LIMIT " . $start . ", 10");
$result = mysql_query($query);

Ok, I see what your trying to do.

replace:

php Code:

Original - php Code
$query = "SELECT count(*) as count FROM guitardb"; $result = mysql_query($query); $row = mysql_fetch_array($result); $numrows = $row['count'];

 
$query = "SELECT count(*) as count FROM guitardb"; 
$result = mysql_query($query);
$row = mysql_fetch_array($result);
$numrows = $row['count'];

with unique variable names.

Also, change:

php Code:

Original - php Code
$query = ("SELECT * FROM guitardb LIMIT " . $start . ", 10");

 
$query = ("SELECT * FROM guitardb LIMIT " . $start . ", 10");

to"

php Code:

Original - php Code
$query = ("SELECT * FROM guitardb LIMIT " . $start . ", ".($start + 10).");

 
$query = ("SELECT * FROM guitardb LIMIT " . $start . ", ".($start + 10).");

Hope that helps.

June 26th, 2002, 08:20 PM

russ

Join Date: Apr 2007

Location: London, UK

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RE: RE: prev next link headache

Quote:

php Code:

Original - php Code
$query = "SELECT count(*) as count FROM guitardb"; $result = mysql_query($query); $row = mysql_fetch_array($result); $numrows = $row['count'];

 
$query = "SELECT count(*) as count FROM guitardb"; 
$result = mysql_query($query);
$row = mysql_fetch_array($result);
$numrows = $row['count'];

with unique variable names.

I'm sorry, but I have no idea what your talking about

June 27th, 2002, 09:46 PM

Taoism

Contributing User

Join Date: Apr 2007

Location: Winnipeg, MB, Canada

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RE: prev next link headache

Code with comments (I reformatted a bit, sorry):

php Code:

Original - php Code

<?php

if($_GET['action']=='sortby'){
 $result=mysql_query("select * FROM guitardb WHERE band LIKE '".strtoupper($_GET['char'])."%' ORDER BY band ASC LIMIT 10",$db); 
 while($myrow=mysql_fetch_array($result)){
 echo " ".$myrow['band']." - <a href=?action=view&id=".$myrow[id]." class=link>".$myrow['song']."</a>";
 }
 //try:
 //if(isset($_GET['start'])){$start=$_GET['start'];}
 //else{$start=0;}
 if(!isset($start)){$start=0;}
 
 $query=("SELECT * FROM guitardb LIMIT ".$start.", 10");
 $result=mysql_query($query);
 //the above query is never actually used for anything
 //because you immediately use the same $result identifier
 //in the query below.
 
 $query="SELECT count(*) as count FROM guitardb"; 
 //change this $result variable to $result2 in order to
 //keep the results of the above query
 $result=mysql_query($query);
 $row=mysql_fetch_array($result);
 $numrows=$row['count'];
 
 //you start a paragraph, but never close it
 //this is more of an HTML gripe than anything.
 echo "";
 if($start>0){
 echo "<a href=?action=sortby&char=".strtoupper($_GET['char'])."&start=".($start - 10)." class=link>Previous</a> ";
 }
 
 //perhaps try:
 //if(($numrows-$start-10)>10){
 // echo "<a href=?action=sortby&char=".strtoupper($_GET['char'])."&start=".($start + 10)." class=link>Next</a>";
 //}else{
 // echo "<a href=?action=sortby&char=".strtoupper($_GET['char'])."&start=".($start)." class=link>Next</a>";
 //}
 if($numrows>($start+10)){
 echo "<a href=?action=sortby&char=".strtoupper($_GET['char'])."&start=".($start + 10)." class=link>Next</a>";
 }
}elseif($_GET['action']=='view'){
 $result=mysql_query("SELECT * FROM guitardb WHERE id=$id",$db); 
 $myrow=mysql_fetch_array($result); 
 
 //why is this blocked?
 //I am assuming a while loop should be here... 
 //and the above fetch_array should be part of it?
 {
 echo "<pre>";
 echo $myrow['tab'];
 echo "</pre>";
 }
 //above output compressed...no biggie...
 //echo "<pre>".$myrow['tab']."</pre>";
 
}else{
 $result=mysql_query("SELECT * FROM guitardb ORDER BY id desc LIMIT 50",$db); 
 while($myrow = mysql_fetch_array($result)){
 echo " ".$myrow['band']." - <a href=?action=view&id=".$myrow[id]." class=link>".$myrow['song']."</a>";
 }
}
?>

 
<?php
 
if($_GET['action']=='sortby'){
  $result=mysql_query("select * FROM guitardb WHERE band LIKE '".strtoupper($_GET['char'])."%' ORDER BY band ASC LIMIT 10",$db); 
  while($myrow=mysql_fetch_array($result)){
    echo "<br>".$myrow['band']." - <a href=?action=view&id=".$myrow[id]." class=link>".$myrow['song']."</a>";
  }
  //try:
  //if(isset($_GET['start'])){$start=$_GET['start'];}
  //else{$start=0;}
  if(!isset($start)){$start=0;}
  
  $query=("SELECT * FROM guitardb LIMIT ".$start.", 10");
  $result=mysql_query($query);
  //the above query is never actually used for anything
  //because you immediately use the same $result identifier
  //in the query below.
  
  $query="SELECT count(*) as count FROM guitardb"; 
  //change this $result variable to $result2 in order to
  //keep the results of the above query
  $result=mysql_query($query);
  $row=mysql_fetch_array($result);
  $numrows=$row['count'];
  
  //you start a paragraph, but never close it
  //this is more of an HTML gripe than anything.
  echo "<p>";
  if($start>0){
    echo "<a href=?action=sortby&char=".strtoupper($_GET['char'])."&start=".($start - 10)." class=link>Previous</a> ";
  }
  
  //perhaps try:
  //if(($numrows-$start-10)>10){
  //  echo "<a href=?action=sortby&char=".strtoupper($_GET['char'])."&start=".($start + 10)." class=link>Next</a>";
  //}else{
  //  echo "<a href=?action=sortby&char=".strtoupper($_GET['char'])."&start=".($start)." class=link>Next</a>";
  //}
  if($numrows>($start+10)){
    echo "<a href=?action=sortby&char=".strtoupper($_GET['char'])."&start=".($start + 10)." class=link>Next</a>";
  }
}elseif($_GET['action']=='view'){
  $result=mysql_query("SELECT * FROM guitardb WHERE id=$id",$db); 
  $myrow=mysql_fetch_array($result); 
  
  //why is this blocked?
  //I am assuming a while loop should be here... 
  //and the above fetch_array should be part of it?
  {
    echo "<pre>";
    echo $myrow['tab'];
    echo "</pre>";
  }
  //above output compressed...no biggie...
  //echo "<pre>".$myrow['tab']."</pre>";
  
}else{
  $result=mysql_query("SELECT * FROM guitardb ORDER BY id desc LIMIT 50",$db); 
  while($myrow = mysql_fetch_array($result)){
    echo "<br>".$myrow['band']." - <a href=?action=view&id=".$myrow[id]." class=link>".$myrow['song']."</a>";
  }
}
?>

Cheers,
Keith.

June 28th, 2002, 03:04 AM

russ

Join Date: Apr 2007

Location: London, UK

Posts: 129

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RE: prev next link headache

Thanks man for your help, actually with your extra comments on the side it helped me understand php alot more, I found the problem in the end, basicly i changed this

php Code:

Original - php Code
if($_GET['action']=='sortby'){ $result=mysql_query("select * FROM guitardb WHERE band LIKE '".strtoupper($_GET['char'])."%' ORDER BY band ASC LIMIT 10",$db);

 
if($_GET['action']=='sortby'){
 
  $result=mysql_query("select * FROM guitardb WHERE band LIKE '".strtoupper($_GET['char'])."%' ORDER BY band ASC LIMIT 10",$db);

to this

php Code:

Original - php Code
if($_GET['action']=='sortby'){ $result=mysql_query("select * FROM guitardb WHERE band LIKE '".strtoupper($_GET['char'])."%' ORDER BY band ASC LIMIT " .$_GET['start'] . ", 10",$db);

 
if($_GET['action']=='sortby'){
 
  $result=mysql_query("select * FROM guitardb WHERE band LIKE '".strtoupper($_GET['char'])."%' ORDER BY band ASC LIMIT " .$_GET['start'] . ", 10",$db);

Altho I do get Prev. and Next Links on everypage.
but as I got that kinda worked out, can i get rid of this section of code?

php Code:

Original - php Code
$query = ("SELECT * FROM guitardb LIMIT " . $start . ", 10"); $result = mysql_query($query); $query = "SELECT count(*) as count FROM guitardb"; $result = mysql_query($query); $row = mysql_fetch_array($result); $numrows = $row['count'];

 
$query = ("SELECT * FROM guitardb LIMIT " . $start . ", 10");
 
 
 
$result = mysql_query($query); 
 
 
 
 
 
$query = "SELECT count(*) as count FROM guitardb"; 
 
$result = mysql_query($query);
 
$row = mysql_fetch_array($result);
 
$numrows = $row['count'];

June 28th, 2002, 04:10 AM

Taoism

Contributing User

Join Date: Apr 2007

Location: Winnipeg, MB, Canada

Posts: 81

Time spent in forums: 30 sec
Reputation Power: 3

RE: prev next link headache

More code with a few tweaks...

php Code:

Original - php Code

 
<?php
if($_GET['action']=='sortby'){
  if(isset($_GET['start'])){$start=$_GET['start'];}else{$start=0;}
    $result=mysql_query("select * FROM guitardb WHERE band LIKE '".strtoupper($_GET['char'])."%' ORDER BY band ASC LIMIT " .$start.", 10",$db); 
  while($myrow=mysql_fetch_array($result)){echo "<br/>".$myrow['band']." - <a href=?action=view&id=".$myrow[id]." class=link>".$myrow['song']."</a>";}
 
  $query="SELECT count(*) as count FROM guitardb"; 
  $result=mysql_query($query);
  $row=mysql_fetch_array($result);
  $numrows=$row['count'];
 
  //you start a paragraph, but never close it
  //this is more of an HTML gripe than anything.
  echo "<p>";
  if($start>0){echo "<a href=?action=sortby&char=".strtoupper($_GET['char'])."&start=".($start - 10)." class=link>Previous</a> ";}
 
  //perhaps try:
    $start_val=(($numrows-$start-10)>10)?($start+10):$start;
    echo "<a href=?action=sortby&char=".strtoupper($_GET['char'])."&start=$start_val class=link>Next</a>";
    echo '</p>';
}
?>

I think the next prev links will work, but what happens when $start=95 out of 100 records and you go $start+10 and run the query for the next batch?

Also, based on the partial code you wrote, I would keep the $_GET['start'] check in, but move it to the top like I did in this example, or you risk the query bombing if start wasn't set.

Mind you, with that logic, you should also check for $_GET['char'] and default it as well if someone removes it from the URL. Or display an error message if it isn't passed in, etc.

Test your forward previous links all the way to the end of your recordset (and make sure the total number of records isn't a multiple of 10. If it works, the all is good

I think I left checking the start and end of the recordset out of my code...but I am too tired to look right now

Cheers,
Keith

#10

June 29th, 2002, 11:20 PM

russ

Join Date: Apr 2007

Location: London, UK

Posts: 129

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RE: prev next link headache

Thank you man, it works now, but I still get prev and next on everypage, but thats a minor fault. thanks again

#11

August 23rd, 2002, 08:32 PM

russ

Join Date: Apr 2007

Location: London, UK

Posts: 129

Time spent in forums: < 1 sec
Reputation Power: 3

RE: prev next link headache

okay, I worked out why I have a prev and next on each page, it seems that it counts how many rows there are in the table instead of counting just the rows being display, ie, if I display just the rows starting with A, it shows just the A's, but it counts all the rows, any way around this? also how can I have a displaying 5 of 19 reviews or something like that?

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