Basic PDO commands to access and manipulate MySQL database

Ok. Now that we have PDO and sakila sample database installed we can begin writing our first code of accesing and showing database data.

Open Netbeans and open the HelloWorldPHP project that we hava in early posts created. Open the index.php file in the editor. Now we need to create connection to MySQL if we want to use the sakila database.

first we write try, catch block and write out our connection strings:


$hostname = "localhost";
$usernameMySQL = "root";
$passwordMySQL = "root";


try{
     ////connection code
}catch(PDOException $exp){
     /////exception code
}

In my case username and pass to MySQL are root, root
Ok so the connection code would be this:

$pdo = new PDO("mysql:host=$hostname;dbname=sakila", $usernameMySQL, $passwordMySQL);
echo "I have succesfully connected to database";

We create $pdo object which gets three parameters: name of the host and type of database driver. In my case that is localhost and mysql. So it can be other host name if the database is hosted on remote server. For dbname we write sakila the name of our db.

The exception code would be this:

 echo $exp->getMessage();

Exception code writes the error message that was took when error occured while connecting.Try, catch block is useful in cases we want to redirect the user to an error page when some error occurs, in our case we would make error page and write some text in it to notify user that there is a problem. So now my index page looks lie this:
            
$hostname = "localhost";
$usernameMySQL = "root";
$passwordMySQL = "root";
         
try{
            $pdo = new PDO("mysql:host=$hostname;dbname=sakila", $usernameMySQL, $passwordMySQL);     
       echo "I have succesfully connected to database";
}catch(PDOException $exp){           
       echo $exp->getMessage();
}
         
Now that we have successfully connected to MySQL we need to prepare some SQL statements in order to use sakila db data. 

In the try block below the echo statement write this code:

$sql="select title from film";
$stmt=$pdo->prepare($sql);
$stmt->execute();
$filmTitles=$stmt->fetchAll();

We are creating sql statement to select only the title column of the film table.
After that we prepare the sql and return the result to the $stmt variable, short for statement.
Than we execute the sql on to the database.
In the last command we fetch  all table entries that the sql statement returns and put them in array $filmTitles

Below the code for the sql write this code for printing the fetched data:

echo "<table border='1'>";
echo "<tr><td>Film Title</td></tr>";
for ($i=0;$i<sizeof($filmTitles);$i++){
                echo "<tr><td>".($i+1).". ".$filmTitles[$i]['title']."</td></tr>";
}
echo "</table>";

No we parse trought the fetched data with for cycle. $filmTitles is an array of arrays with two elements i.e it is 1000x2 matrix. So we access each element with this code $filmTitles[$i]['title'] and we can see that the subarrays are associative. You can use print_r function to print the data in filmTitles and see whats behind the hood.


Try this in your php code after the for

print_r($filmTitles); 

 This is the basic setup for PDO data access to database. More tuts on this to come :)

Installing PDO on Ubuntu

Requirements for this post:

Installed php 5.1+ engine, apache2 web server
installed Netbeans 7 or 6.9
Installed MySQL and MySQL WB.

If you havent already installed this visit my older posts and install whats missing.

So in this post I will explain what is PDO and how can be installed on Ubuntu/Windows.

PDO stands for PHP Data Objects. It is PECL extension for PHP 5.0 and ships with PHP 5.1 and newer versions of PHP. It is dependent on OO features of PHP so it will not work in older PHP versions.

It is data-access abstraction layer  which means that you can use same function for access and manipulation of db data no mather what type of db is behind. So depending on the type of the db behind, you use special PDO driver for that database.  Here is the official PDO docs PDO .

PDO is not dependent of other libraries and extensions so if you have PHP 5.0+ you are ready to go and install.

PDO is a PECL extension so you will need this package in order to install pdo php5-dev.

Open terminal and run this command:

$sudo apt-get install php5-dev

 No we will install PDO.

The easiest way to install on Ubuntu is to use these commands:

$ sudo apt-get install libmysqlclient15-dev
$ sudo pecl install pdo
$ sudo pecl install pdo_mysql

 I have PHP 5.3 so no need to edit the php.ini file. If you have other version 

you should edit the php.ini file and add these lines 

extension=pdo.so
extension=pdo_mysql.so

On PHP 5.3 php.ini is place in the /etc/php5/apache2 folder. 

On other PHP versions it should be in /etc/php5/cgi/php.ini or /etc/php/cli/php.ini.

So no open terminal and run this command 

$ sudo gedit /path/to/php.ini 

mine was 

$sudo gedit /etc/php5/apache2/php.ini

It will open text file. Find the Dynamic extensions section and add the lines

extension=pdo.so
extension=pdo_mysql.so 

Now save the file and close it. In terminal run 

$ sudo /etc/init.d/apache2 restart 

to restart the web server.   Now I will create a test project in Netbeans to test 

the installtion of PDO. 

In previous post I created new PHP project called HelloWorldPHP. If you haven't 

I will explain it again here. 

Open Netbeans and click file->new project. Choose new PHP application 

and click next. Add the name of the project HelloWorldPHP and place it in the 

sources folder /var/www/HelloWorldPHP. Click finish. This will open new 

project in the projects panel. 

Now, click right click on the  HelloWorldPHP node and click 

set as main project. Open the sources folder and double click the index.php file

It will open in the editor window. Now you will see a php segment 

<?php ?>
 

Add this line of code phpinfo(); 

Your page will look like 

<?php phpinfo(); ?>
 

Now open a browser and type this url: http://localhost/HelloWorldPHP/ 

or click run->run main project in Netbeans. You  should get the php info 

page with all settings. Now far below on the page you have to find PDO 

section and pdo_mysql section. If this is the case than you installed it succesfully. 

Otherwise check what's wrong and post a question. 

In the next post i will add some on installing PDO on Windows.