How to Connect Database in PHP Using OOPS

How to set up a database connection, using Object-Oriented Programming (OOP), PHP and MySQL. Below following step:

Step 1: To create files DatabaseClass.php and write a class with a function( query_executed,get_rows,get_fetch_data ).

class DatabaseClass
{
private $host = "localhost"; // your host name
private $username = "root"; // your user name
private $password = ""; // your password
private $db = "test_db"; // your database name
public
function __construct()
{
mysql_connect($this - > host, $this - > username, $this - > password) or die(mysql_error("database"));
mysql_select_db($this - > db) or die(mysql_error("database"));
}
// this method used to execute mysql query
protected
function query_executed($sql)
{
$c = mysql_query($sql);
return $c;
}
public
function get_rows($fields, $id = NULL, $tablename = NULL)
{
$cn = !emptyempty($id) ? " WHERE $id " : " ";
$fields = !emptyempty($fields) ? $fields : " * ";
$sql = "SELECT $fields FROM $tablename $cn";
$results = $this - > query_executed($sql);
$rows = $this - > get_fetch_data($results);
return $rows;
}
protected
function get_fetch_data($r)
{
$array = array();
while ($rows = mysql_fetch_assoc($r))
{
$array[] = $rows;
}
return $array;
}
}

Step 2: Create index.php file,

<?php
include("DatabaseClass.php");
$obj = new DatabaseClass ();
$a = $obj-> get_rows (implode(",",array("ID","post_date","post_title")), '' , "tablenane") ; // there are pass two parameters one is table fields and second is table name
echo "<pre>";
print_r($a);
echo "</pre>";
?>

Output: