[Code] PHP - Database connection class

[Tuesday]

Hi there. Today I'm going to learn you about Mysql Database connection using a class.

Requirements
- PHP5 Server (not 4 )
- Basic knowledge of PHP (See my other tutorial)



Normally you would connect to a mysql database like this:

PHP Code:

			
$link = mysql_connect("localhost", "user", "password");

if ($link) {

        die('Could not connect: ' . mysql_error());

}

mysql_select_db("Databasename");

$result = mysql_query("SELECT * FROM `tablename` LIMIT 30");

mysql_close($link); 




		

However, that's a little bit messy and it would be useless if you have to place mysql_connect/close in every PHP file. And if your user or password changed, you have to edit ALL the PHP files... isn't nice.

So you can do this with a class and a config file (config.php). For example:

config.php

PHP Code:

			
<?php

    define("DB_HOST", "localhost");

    define("DB_USER", "username");

    define("DB_PW", "password");

    define("DB_NAME", "databasename");

?>


		

database.php

PHP Code:

			
<?php

class database {

    private $dblink;

    function __construct($configfile) {

        require_once($configfile);

        $this->dblink = mysql_connect(DB_HOST, DB_USER, DB_PW);

        if (!$this->dblink) {

            exit('Could not connect: ' . mysql_error());

        }

        mysql_select_db(DB_NAME);

    }

    function query($sql) {

        $res = mysql_query($sql);

        if (!$res) {

            echo "<strong>Error:</strong> ".mysql_error()."\n<br />";

        }

        return $res;

    }

    function count_rows($sql) {

        $res = mysql_query($sql);

        $crows = 0;

        if ($res) $crows = mysql_num_rows($res);

        return $crows;

    }

    function __destruct() {

        mysql_close($this->dblink);

    }

}

?>


		

index.php

PHP Code:

			
require_once('database.php');

$db = new database('config.php');

echo $db->count_rows("SELECT * FROM tablename LIMIT 100");

$result = $db->query('SELECT * FROM tablename LIMIT 100'); 




		

As you can see it's shorter and it has 1 config file.
The database class could use a better error handling, but it's just an example, don't shoot me.
Good luck,
Tuesday

[RiSiCO]

A good tutorial, as always

[dikamilo]

Better use PDO in php5, it's easier and works with a lot of db.

PHP: PDO - Manual

Example

Code:

$pdo = new PDO('mysql:host=localhost;dbname=myname', 'user', 'password');

$pdo -> query('SELECT * FROM users');

[Tuesday]

Quote Originally Posted by dikamilo

Better use PDO in php5, it's easier and works with a lot of db.

PHP: PDO - Manual

Yes that's also a way to do it.

I added code highlighting (so using [ php ] and [ html ] instead of [ code ]) to all my tutorials:
Basics of PHP
Basic Javascript animations
PHP5 - Basics of Classes