Why dont you create your own CMS???--Part 4

Creating the database class file

Here we are going to create a simple class file for carrying database functions.

• Open stupid>>include directory.
• create file and name it as 'database_class.php'.

In our database class file,we will have property named connection.Here is what our class file looks like.

<?php
class Database  {
 var $connection;
 
 function __construct()
 {
 $conn=@mysql_connect(DB_HOST,DB_USER,DB_PASS);
 if(!$conn)
  {
  die("Cannot connect to database");
  }
  else
  {
  $this->connection=$conn;
  $this->select_db(DB_NAME);
  //echo "connected";
  }
 }

 /**************************
   select db
 ***************************/
 private function select_db($db)
 {
 if(!@mysql_select_db($db,$this->connection))
  {
  die("Cannot select database");
  }
 else
  {
  //echo "yes I GOT IT!!!";
  }
 }
 
 /****************************
   QUERY
 *******************************/
 public function query($sql)
 {
 $result=@mysql_query($sql,$this->connection);
 if(!$result)
  {
  die("SQL Error");
  }
 else
  {
  return $result;
  }
 }

 /*****************************
   fetch object
 *******************************/
 public function fetch_obj($result)
 {
 return mysql_fetch_object($result);
 }
 
 public function fetch_array($result)
 {
 return mysql_fetch_array($result);
 }
 
 
 /******************************
   fetch number
 ****************************/
 public function fetch_num($result)
 {
 return mysql_num_rows($result);
 }
   
}

?>

Lets have a quick look at the functions (methods) used.

1] __construct()
              
There is no need of talking much about the constructor.This function is automatically called during class instantiation.In the constructor we are making a connection to database.The arguments in @mysql_connect() function are constants we defined in our 'base.php' file.If connection is established ,database is selected by calling the select_db method.

2] select_db()
                 
 This method selects the database

3] query()
                 
 To do a mysql query and return a result.

4]fetch_object(),fetch_array()
                 
 Both these methods have an argument which is usually the result returned from the query method.The former returns the result as an object,the latter as an array.

5]fetch_num()
                   
This method is used to return the number of rows affected.

THIS IS A SIMPLE CLASS FILE AND  NOT AN ADVANCED DATABASE CLASS FILE .
But you can use this for simple database operations.
The class instantiation will look like

$db= new Database();

We will instantiate all our class files in a single file.I just mentioned it as an example.So if we need to call any method in database class, we will use '->'
for example, to do a  query ,

$db->query("YOUR-QUERY-HERE");

In the next post we will have a look at our next class file 'theme_class.php' to handle themes.

<<<PREVIOUS || NEXT>>>