PHP MySQL OOP (mysqli)

CREATE TABLE `customer` (
  `CustomerID` varchar(4) NOT NULL,
  `Name` varchar(50) NOT NULL,
  `Email` varchar(50) NOT NULL,
  `CountryCode` varchar(2) NOT NULL,
  `Budget` double NOT NULL,
  `Used` double NOT NULL,
  PRIMARY KEY  (`CustomerID`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

INSERT INTO `customer` VALUES ('C001', 'Win Weerachai', '[email protected]', 'TH', 1000000, 600000);
INSERT INTO `customer` VALUES ('C002', 'John  Smith', '[email protected]', 'UK', 2000000, 800000);
INSERT INTO `customer` VALUES ('C003', 'Jame Born', '[email protected]', 'US', 3000000, 600000);
INSERT INTO `customer` VALUES ('C004', 'Chalee Angel', '[email protected]', 'US', 4000000, 100000);

<?php

	ini_set('display_errors', 1);
	error_reporting(~0);

	$serverName = "localhost";
	$userName = "root";
	$userPassword = "root";
	$dbName = "mydatabase";

	$conn = new mysqli($serverName,$userName,$userPassword,$dbName);

	if ($conn->connect_errno) {
		echo $conn->connect_error;
		exit;
	}
	else
	{
		echo "Database Connected.";
	}

	$conn->close();
?>

<?php
	ini_set('display_errors', 1);
	error_reporting(~0);

	$serverName = "localhost";
	$userName = "root";
	$userPassword = "root";
	$dbName = "mydatabase";

	$conn = new mysqli($serverName,$userName,$userPassword,$dbName);

	$sql = "SELECT * FROM customer";

	$query = $conn->query($sql);
	//$query->num_rows;
	$result = $query->fetch_assoc();
	if($result)
	{
		echo $result["CustomerID"]."<br>";
		echo $result["Name"]."<br>";
		echo $result["Email"]."<br>";
		echo $result["CountryCode"]."<br>";
		echo $result["Budget"]."<br>";
		echo $result["Used"]."<br>";
	}
	$conn->close();

?>

<?php
	ini_set('display_errors', 1);
	error_reporting(~0);

	$serverName = "localhost";
	$userName = "root";
	$userPassword = "root";
	$dbName = "mydatabase";

	$conn = new mysqli($serverName,$userName,$userPassword,$dbName);

	$sql = "SELECT * FROM customer";

	$query = $conn->query($sql);
	//$query->num_rows;

	while($result = $query->fetch_assoc())
	{
		echo $result["CustomerID"]."<br>";
		echo $result["Name"]."<br>";
		echo $result["Email"]."<br>";
		echo $result["CountryCode"]."<br>";
		echo $result["Budget"]."<br>";
		echo $result["Used"]."<br>";
		echo "<hr>";
	}
	$conn->close();

?>

<?php
	ini_set('display_errors', 1);
	error_reporting(~0);

	$serverName = "localhost";
	$userName = "root";
	$userPassword = "root";
	$dbName = "mydatabase";

	$conn = new mysqli($serverName,$userName,$userPassword,$dbName);

	// Insert
	$sql = "INSERT INTO customer (CustomerID, Name, Email, CountryCode, Budget, Used) 
		VALUES ('C005','Weerachai Nukitram','[email protected]'
		,'TH','6000000','0')";
	$query = $conn->query($sql);

	// Update
	$sql = "UPDATE customer  SET Used = '100000' WHERE CustomerID = 'C005' ";
	$query = $conn->query($sql);

	// Delete
	$sql = "DEELTE FROM customer  WHERE CustomerID = 'C005' ";
	$query = $conn->query($sql);

	if($query)
	{
		// result suscess
	}

	$conn->close();

?>