PHP Recordset Paging

In this tutorial, we first look at creating a page that displayed the results of a database query, and showing all results returned to the user.

Imagine that you have a recordset containing 100 records, for example. Usually you wouldn't want to display all 100 records at once, as it's far too much information for a web site visitor to take in at once, and it can also make your web pages slow to load. Instead, it's much more desirable to be able to show the user 10 records at a time for example, and let them move back and forth between pages. A perfect example of this is a search engine such as Google, although it can be used on any web site that uses dynamic data.

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Overview

In this tutorial, we first look at creating a page that displayed the results of a database query, and showing all results returned to the user. We then look at the MySQL LIMIT command, which returns only certain records from the results obtained by a query, meaning you only get the records you are actually going to use, creating faster and more efficient queries. We use the LIMIT command to adapt our existing code so that it showed the results in pages of 5 records to a page.

We then create a dynamic navigation bar, which allows the users to quickly move backwards and forwards between pages. Finally we alter the code so that if results of a search are being shown, the search parameters are preserved as the user moves from page to page.

 

Table of Content:

  • What is Recordset Paging?
  • Step 1 - Creating some Example Data
  • Step 2 - Creating a Database Connection File
  • Step 3 - Creating Code to Create and Display a Recordset
    • 3.1 Creating the PHP code to read records from the Database
    • 3.2 Creating the HTML and PHP to display the Results
    • 3.3 Testing the Page
  • Step 4 - Adding Recordset Paging
    • 4.1 - The MySQL LIMIT command
    • 4.2 Adapting the existing code
    • 4.3 Creating a Dynamic Navigation Bar
    • 4.4 Testing the Complete Page
    • 4.5 - Using the Recordset Pages with the Results of a Search
  • Summary

4.4 Testing the Complete Page

All that's left to do now is to test the completed page in your browser.

You should initially see a display similar to the one below:

Figure 5 - Page showing First Page of Records

Note that because this is the first page of records there is no previous page button displayed. If you click on 2 or the next page button, you should see a result similar to Figure 6 below.

Figure 6 - Page showing Second Page of Records

Note that because this is the second page, the previous page button (<<) is displayed.

4.5 - Using the Recordset Pages with the Results of a Search

In the example so far we've shown all records from the example_data table. We'll finish up by looking at how to create recordset pages that show the results of a search.

Save the recordset_paging.php page as recordset_paging_search.php.  Again you can if you wish download the completed page from http://www.garethdp.com/writing/articles/dmxzone/code/recordsetpaging/.

We will modify the page so that it displays only tutorials written by a particular author, where the authors name is specified in a URL parameter called author.

Switch to Code View, and make the changes shown in blue below to the first block of PHP code at the very top of the page.

<?php
// Include Database Connection File
require_once("G:/webserver/DMXZone/recordset_paging/includes/dbConnection.php");
// Open Database Connection
$dbLink = mysql_connect($dbHost, $dbUser, $dbPass);
if (!$dbLink){ die ("Database: Couldn`t connect to mySQL Server"); }
mysql_select_db($dbName, $dbLink) or die ("Database: Couldn`t open Database");
// Build SQL query to find Total Number of Records
$sql  = "SELECT id ";
$sql .= "FROM example_data ";
$sql .= "WHERE author='" . $_GET['author'] . "'";
// Read in Total Number of Records
$dbResult = mysql_query($sql, $dbLink) or die ("MySQL Error: " . mysql_error() );
$totalRecords = mysql_num_rows($dbResult);
// Calculate Number of Pages Required
$recordsPerPage = 5;
$totalPageNumber = ceil($totalRecords / $recordsPerPage);
// Check for Page Number
if(strlen($_GET['page']) < 1){
     $currentPage = 1;
} else {
     $currentPage = $_GET['page'];
}
// Create Offset Number
$offset  = ($currentPage * $recordsPerPage) - $recordsPerPage;
// Create New SQL Query
$sql  = "SELECT UNIX_TIMESTAMP(date) as dateTime,id,title,author ";
$sql .= "FROM example_data ";
$sql .= "WHERE author='" . $_GET['author'] . "'";
$sql .= "ORDER BY UNIX_TIMESTAMP(date) DESC ";
$sql .= "LIMIT " . $offset . "," . $recordsPerPage;
// Execute SQL Query and Read in Records
$dbResult = mysql_query($sql, $dbLink) or die ("MySQL Error: " . mysql_error() );
$numRecords = mysql_num_rows($dbResult);
$recordset = "";
for($i=0;$i<$numRecords;$i++){
  $recordset[] = mysql_fetch_assoc($dbResult);
}  
// Close Database Connection 
mysql_close($dbLink);
?>

Code Block 8 - Changes required to the first block of PHP code

Here we've added a simple WHERE clause to the SQL queries as shown below:

$sql .= "WHERE author='" . $_GET['author'] . "'";

This filters the records so that it only retrieves the records where the authors name matches the name in the URL parameter author.

You can now test the page, by using a URL similar to the one below:

recordset_paging_search.php?author=Gareth+Downes-Powell

You can see that the records shown are only ones written by myself. However, we have a problem in that if you use the navigation bar, the search parameter author isn't passed from page to page so the search fails. We can easily remedy this by changing the block of code that creates the navigation bar to:

<?php
// Create Dynamic Navigation Bar
$pageURL = $_SERVER['SCRIPT_NAME'];
$html = "";
if($currentPage > 1){
     // Create Previous Page Link (<<)
     $url = $pageURL . "?page=" . ($currentPage - 1) . "&author=" . $_GET['author'];
     $html .= "<a href='" .  $url . "'> << </a>";
     $html .= "&nbsp;";
}
for($i=1; $i <= $totalPageNumber; $i++){
     // Create Numerical Page Links ( 1 2 3 etc )
     $url = $pageURL . "?page=" . $i . "&author=" . $_GET['author'];
     $html .= "<a href='" .  $url . "'>" . $i . "</a>";
     $html .= "&nbsp;";
}
if($currentPage < $totalPageNumber){
     // Create Next Page Link (>>)
     $url = $pageURL . "?page=" . ($currentPage + 1) . "&author=" . $_GET['author'];
     $html .= "<a href='" .  $url . "'> >> </a>";
     $html .= "&nbsp;";
}
?>

Code Block 9 - Changes to the Navigation Bar code to preserve the Search Parameters

In code block 9 above the changes required are highlighted in blue.  You can see that we are just adding the contents of the URL author parameter onto the end of the link, so that it's preserved as the user moves from page to page and the search returns the correct results still.

You can see example output in Figure 7 below.

Figure 7 - Page showing Search Results and using Recordset Paging

Gareth Downes-Powell

Gareth Downes-PowellGareth has a range of skills, covering many computer and internet related subjects. He is proficient in many different languages including ASP and PHP, and is responsible for the setup and maintenance of both Windows and Linux servers on a daily basis.


In his daily web development work he uses the complete range of Macromedia software, including Dreamweaver MX, Flash MX, Fireworks MX and Director to build a number of websites and applications. Gareth has a close relationship with Macromedia, and as a member of Team Macromedia Dreamweaver, he has worked closely in the development of Dreamweaver, and was a beta tester for Dreamweaver MX.


On a daily basis he provides support for users in the Macromedia forums, answering questions and providing help on a range of different web related subjects. He has also written a number of free and commercial extensions for Dreamweaver MX, to further extend its capabilities using its native JavaScript API’s or C++.


As a web host, Gareth has worked with a range of different servers and operating systems, with the Linux OS as his personal favourite. Most of his development work is done using a combination of Linux, Apache and MySQL and he has written extensively about setting up this type of system, and also running Apache and MySQL under Windows.

See All Postings From Gareth Downes-Powell >>

Reviews

nice tutorial

May 24, 2009 by ijaz khattak

dear sir

i am facing a prblem in my project, if u can help me in that i will mail it t you.

thanks 

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