PHP查询MySQL查询没有正确递增/递减

Question

I'm having trouble with the follow PHP which paginates the results of a MySQL query.

When I go to webpagename.php with the first page of the results and click Previous, the browser changes to webpagename.php?page=-1 and shows the first page of results again. If I click Previous again, it changes to webpagename.php?page=-2 and shows Page 1 of the results again, etc.

When I go to webpagename.php with the first page of the results and click Next, the browser changes to webpagename.php?page=1 and shows the first page of results again. I then have to hit Next a second time to move to Page 2.

When I go to the last page of the results - Page 8 - and click Next, the browser changes to webpagename.php?page=9 and shows Page 1 of the results. If I click Next again, it shows webpagename.php?page=10 and shows Page 1 of the results again, etc.

Expected Results:

When on Page 1 and a user hits Previous, I would like the code to do nothing/not decrement. When on Page 8 - the last page of results, I would like the code to do nothing/not increment. Of course, I would also expect that if you hit Next from Page 1 that it doesn't display Page 1 a second time but rather goes to Page 2.

Your exact changes to this code to make it work properly are very much appreciated. Thank you for time.

<?php

mysql_connect("localhost","username","password") or die(mysql_error());
mysql_select_db("dbname") or die(mysql_error());


// number of results to show per page
$per_page = 10;


// figure out the total pages in the database
$result = mysql_query("SELECT * FROM uc_users LEFT JOIN ent_dancers ON uc_users.id = ent_dancers.id WHERE ent_dancers.DancerYesNo = '1' AND ent_dancers.DancerEnabledYesNo = '1' ORDER BY uc_users.display_name ASC");

$total_results = mysql_num_rows($result);

$total_pages = ceil($total_results / $per_page);


// check if the 'page' variable is set in the URL (ex: webpagename.php?page=1)
if (isset($_GET['page']) && is_numeric($_GET['page']))

{
        $show_page = $_GET['page'];


        // make sure the $show_page value is valid
        if ($show_page > 0 && $show_page <= $total_pages)

        {
                $start = ($show_page -1) * $per_page;

                $end = $start + $per_page; 

        }
        else

        {
                // error - show first set of results

                $start = 0;

                $end = $per_page; 

        }               
}

else
{

        // if page isn't set, show first set of results
        $start = 0;

        $end = $per_page; 

}

// display pagination

// display data in table

    echo "<div class='dancerbio'>";
    echo "<div class='uts-1'>";

// loop through results of database query, displaying them in the table 
for ($i = $start; $i < $end; $i++)

{
        // make sure that PHP doesn't try to show results that don't exist

        if ($i == $total_results) { break; }


        // echo out the contents of each row into a table



        $rowid = mysql_result($result, $i, 'id'); 

        echo "<div class='uts-1-1'><a class='bodytxt5' href='webpagename-details.php?userid=$rowid'>" . mysql_result($result, $i, 'display_name') . "</a></div>";


}

// close table>
    echo "<div class='ugen-1'></div>";
    echo "</div>";

$prev = $_GET['page'] - 1;

echo "<div style='clear:both;height:1px;overflow: hidden;'></div>";

echo "<br /><a class='bodytxt5' href='webpagename.php?page=" . $prev . "'>Prev</a>&nbsp;&nbsp;";

for ($i = 1; $i <= $total_pages; $i++)

{
        echo "<a class='bodytxt5' href='webpagename.php?page=$i'>$i</a>&nbsp;&nbsp;";

}

$next = $_GET['page'] + 1;

echo "&nbsp;<a class='bodytxt5' href='webpagename.php?page=" . $next . "'>Next</a>&nbsp;";
echo "</div>";


// pagination

?>

Answer 1

replace this:

 if (isset($_GET['page']) && is_numeric($_GET['page']))

 {
    $show_page = $_GET['page'];


    // make sure the $show_page value is valid
    if ($show_page > 0 && $show_page <= $total_pages)

    {
            $start = ($show_page -1) * $per_page;

            $end = $start + $per_page; 

    }
    else

    {
            // error - show first set of results

            $start = 0;

            $end = $per_page; 

    }               
  }
  else
  {

    // if page isn't set, show first set of results
    $start = 0;

    $end = $per_page; 

  }

by this:

   if (isset($_GET['page']) && is_numeric($_GET['page']))
   {
       $show_page = $_GET['page'];

       if ($show_page > 0 && $show_page <= $total_pages)
       {
            $start = ($show_page -1) * $per_page;

            $end = $start + $per_page; 
       }
       elseif ($show_page > $total_pages)
       {
            $show_page=$total_pages;
            $start = ($show_page -1) * $per_page;

            $end = $start + $per_page; 

       }
       else {
            $show_page=1;
            $start = 0;

            $end = $per_page; 
       }
 }
 else {
    $show_page=1;
    $start = 0;

    $end = $per_page;
 }

then :

$prev=$show_page-1;
$next=$show_page+1;

if($show_page>1){//this way previsous won't appear if you are at page 1 already
   //show previous div
}

if($show_page<$total_pages){ //this way next won't appear unless you are not at the last page
   //show next div
}