Demo: PHP-MySQL database connection using namespaces

Namespace in PHP:-

Namespace concept isn’t any new for programmers coming from c++, java, python or ruby platform. They are a way of encapsulating classes. You could compare it with package in other programming language, which contains several classes.

Advantages of PHP Namespaces:-

Prevents class collisions of different libraries.
Allow to use class alias to make code more readable.

Defining and importing Namespaces in PHP.

namespace DB; 
// here DB is declared as namespace any code come below will be encapsulated by it.

1 2	namespace DB; // here DB is declared as namespace any code come below will be encapsulated by it.

They can be separated by forward slashes.

namespace \FRAMEWORK\DB\MODELS; 
// but it doesn't mean class DB must reside inside  FRAMEWORK namespace.

1 2	namespace \FRAMEWORK\DB\MODELS; // but it doesn't mean class DB must reside inside FRAMEWORK namespace.

Now to use it,

use \FRAMEWORK\DB\MODELS as model; 
// to import namespace in your application.

1 2	use \FRAMEWORK\DB\MODELS as model; // to import namespace in your application.

Example:- code readability with namespaces

use \DB\MySQL as mysql;

/**
* Creating a new database connection.
* new mysql() creates new Object
*/
$link = new mysql(array(
		'host' => 'localhost',
		'database' => 'curd',
		'username' => 'root',
		'password' => ''
		));

$DB = $link->getConnection()->connectDB();

$users = $DB->query("select * from users")->fetch();

use \DB\MySQL as mysql;

/**

* Creating a new database connection.

* new mysql() creates new Object

$link = new mysql(array(

'host' => 'localhost',

'database' => 'curd',

'username' => 'root',

'password' => ''

));

$DB = $link->getConnection()->connectDB();

$users = $DB->query("select * from users")->fetch();

See the database table structure for above code.

Using namespace in PHP code

We’ll have following file structure to arrange the namespace.

/demo.php
/config.php
/import/
/import/db.php
/import/db/
/import/db/mysql.php
/import/db/mysql/
/import/db/mysql/query.php

/demo.php

/config.php

/import/

/import/db.php

/import/db/

/import/db/mysql.php

/import/db/mysql/

/import/db/mysql/query.php

Make config file with global configuration:-

//File Location: /config.php

define("NAMESPACE_DIR",'import'); 

function __autoload($class) {     
$parts = explode("\\", $class);     
$filepath = implode(DIRECTORY_SEPARATOR,$parts);     
$filepath = strtolower(NAMESPACE_DIR.DIRECTORY_SEPARATOR.$filepath.'.php');     
require $filepath; 
} 

$DB_SETTINGS = array( 	
	'host' => 'localhost',
	'database' => 'curd',
	'username' => 'root',
	'password' => ''
);

global $DB_SETTINGS;

//File Location: /config.php

define("NAMESPACE_DIR",'import');

function __autoload($class) {

$parts = explode("\\", $class);

$filepath = implode(DIRECTORY_SEPARATOR,$parts);

$filepath = strtolower(NAMESPACE_DIR.DIRECTORY_SEPARATOR.$filepath.'.php');

require $filepath;

}

$DB_SETTINGS = array(

'host' => 'localhost',

'database' => 'curd',

'username' => 'root',

'password' => ''

);

global $DB_SETTINGS;

Above code makes default setting for database connection.
we made __autoload() function to specify php how it should load class files.
In our example __autoload() function looks into directory “import”.
Then every namespace would be store as separate directory.
classes within that namespace will be stored inside namespace directory.

Example, see following code

use \DB\MySQL as mysql;

1	use \DB\MySQL as mysql;

___autoload() will look for file into following location.

/import/db/mysql/mysql.php

1	/import/db/mysql/mysql.php

Revisiting basic mysql functions

Function Name	Description
mysql_connect(‘HOSTNAME’,’USER’,’PASSWORD’);	Connects to mysql server.
mysql_select_db(‘DATABASE’);	Select database from mysql
mysql_query(‘SQL’)	Does SQL manipulations
mysql_fetch_row / mysql_fetch_array / mysql_fetch_assoc	Gets SQL results into array.
mysql_close()	Closes Database Connection

Create mysql class into DB package

//File Location: /import/db/mysql.php

namespace DB; 

class MySQL{

protected $host; 	
protected $database; 	
protected $username; 	
protected $password; 	
private $resource_id; 	
public $connection = NULL; 

function __construct($settings = array()) {
                $this->host          = $settings['host'];
		$this->database 	= $settings['database'];
		$this->username 	= $settings['username'];
		$this->password 	= $settings['password'];
                /**
                * if connection already created just return resource_id
                * else create new one
                */
		if( is_null($this->connection) ) {
			$this->getConnection()->connectDB();
		}

		return $this->connection;
	}

	function __destruct() {
		@mysql_close($this->connection);
	}

	public function getConnection(){
/** 
* Native php function to create db_connection
*/	
	$this->connection = @mysql_connect(
				$this->host,
				$this->username,
				$this->password
		);

		if(!$this->connection) {
			die("Unable to create connection, Server might be too busy or check your credentials!");			
		}

		return $this;
	}

	public function connectDB() {
/** 
* Native php function to select database
*/
		if(mysql_select_db($this->database,$this->connection)){
			return $this;
		} else {
			die("Unable to connect to database");
		}
	}

}

//File Location: /import/db/mysql.php

namespace DB;

class MySQL{

protected $host;

protected $database;

protected $username;

protected $password;

private $resource_id;

public $connection = NULL;

function __construct($settings = array()) {

$this->host = $settings['host'];

$this->database = $settings['database'];

$this->username = $settings['username'];

$this->password = $settings['password'];

/**

* if connection already created just return resource_id

* else create new one

if( is_null($this->connection) ) {

$this->getConnection()->connectDB();

}

return $this->connection;

}

function __destruct() {

@mysql_close($this->connection);

}

public function getConnection(){

/**

* Native php function to create db_connection

$this->connection = @mysql_connect(

$this->host,

$this->username,

$this->password

);

if(!$this->connection) {

die("Unable to create connection, Server might be too busy or check your credentials!");

}

return $this;

}

public function connectDB() {

/**

* Native php function to select database

if(mysql_select_db($this->database,$this->connection)){

return $this;

} else {

die("Unable to connect to database");

}

Create query class into MySQL package

//File Location: /import/db/mysql/query.php

namespace DB\Mysql; 
use DB\Mysql as mysql; 

class Query extends mysql{ 

private $resource_id; 	
private $record_set; 

function __construct( $sql ){ 		
  global $DB_SETTINGS; 		
  $this->record_set = Array();
		$this->resource_id = parent::__construct($DB_SETTINGS);	
		$this->query($sql);
	}

	public function query($sql) {
			$this->resource_id = mysql_query($sql,$this->connection);
			if(!$this->resource_id){
				echo (mysql_error());
				return null;
			}
			return $this;
	}

	public function fetch() {
			$record_set = Array();
			while($row = mysql_fetch_assoc($this->resource_id)) {
				$record_set[] = $row;
			}
			return $record_set;
	}	
}

//File Location: /import/db/mysql/query.php

namespace DB\Mysql;

use DB\Mysql as mysql;

class Query extends mysql{

private $resource_id;

private $record_set;

function __construct( $sql ){

global $DB_SETTINGS;

$this->record_set = Array();

$this->resource_id = parent::__construct($DB_SETTINGS);

$this->query($sql);

}

public function query($sql) {

$this->resource_id = mysql_query($sql,$this->connection);

if(!$this->resource_id){

echo (mysql_error());

return null;

}

return $this;

}

public function fetch() {

$record_set = Array();

while($row = mysql_fetch_assoc($this->resource_id)) {

$record_set[] = $row;

}

return $record_set;

}

Creating demo.php file

// File Location: /demo.php

require("config.php"); 

use DB\MySQL\Query as query; 

$users = new query("select * from users"); 
$all_users = $users->fetch(); 

foreach ($all_users as $user): 	
         print $user['name'] . "  ";  	
         print $user['email'] . ""; 
endforeach;

// File Location: /demo.php

require("config.php");

use DB\MySQL\Query as query;

$users = new query("select * from users");

$all_users = $users->fetch();

foreach ($all_users as $user):

print $user['name'] . " ";

print $user['email'] . "";

endforeach;

You could download sample working code here. In upcoming post I’ll explain how to plug mysqli class to this DB package without changing core business logic.

2 Comments

Reply Gaurav | September 17th, 2013

Nice blog, looking forward to see more useful stuff here.
Thanks Vikas. 🙂
Reply Manuel Osuna | September 10th, 2016

Hello there! Your post is so useful. But I have some doubts about it. How do you implement the _autoload fuction in the configuration file?

Vikas's Blog A Tech Blog

Namespace in PHP:-

Advantages of PHP Namespaces:-

Defining and importing Namespaces in PHP.

Example:- code readability with namespaces

Using namespace in PHP code

Make config file with global configuration:-

Revisiting basic mysql functions

Create mysql class into DB package

Create query class into MySQL package

Creating demo.php file

2 Comments

So, what do you think ?