PHP MySQL Prepared Statement / Parameter Query (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);

	$strCustomerID = "C001";
	$sql = "SELECT * FROM customer WHERE CustomerID = ? ";
	$stmt = $conn->prepare($sql);
	$stmt->bind_param('s', $strCustomerID); //   s - string, b - blob, i - int, etc

	/*** for 2 Parameters
		$strCustomerID = "C001";
		$strEmail = "[email protected]";
		$sql = "SELECT * FROM customer WHERE CustomerID = ? AND Email = ? ";
		$stmt = $conn->prepare($sql);
		$stmt->bind_param('ss', $strCustomerID,$strEmail); //   s - string, b - blob, i - int, etc
	**/

	$stmt ->execute();

	$result = $stmt->get_result();
	$row = $result->fetch_assoc();

	if($row)
	{
		echo $row["CustomerID"]."<br>";
		echo $row["Name"]."<br>";
		echo $row["Email"]."<br>";
		echo $row["CountryCode"]."<br>";
		echo $row["Budget"]."<br>";
		echo $row["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);

	$strCountryCode = "US";
	$sql = "SELECT * FROM customer WHERE CountryCode = ? ";
	$stmt = $conn->prepare($sql);
	$stmt->bind_param('s', $strCountryCode); //   s - string, b - blob, i - int, etc

	$stmt ->execute();

	$result = $stmt->get_result();

	while($row = $result->fetch_assoc())
	{
		echo $row["CustomerID"]."<br>";
		echo $row["Name"]."<br>";
		echo $row["Email"]."<br>";
		echo $row["CountryCode"]."<br>";
		echo $row["Budget"]."<br>";
		echo $row["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);

	$strCustomerID = "C005";
	$strName = "Weerachai Nukitram";
	$strEmail = "[email protected]";
	$strCountryCode = "TH";
	$strBudget = "6000000";
	$strUsed = "0";

	$sql = "INSERT INTO customer (CustomerID, Name, Email, CountryCode, Budget, Used) VALUES (?, ?, ?, ?, ?, ?)";
	$stmt = $conn->prepare($sql);
	$stmt->bind_param('ssssii', $strCustomerID, $strName, $strEmail, $strCountryCode, $strBudget, $strUsed); //   s - string, b - blob, i - int, etc

	$stmt ->execute();

	printf("%d Row inserted.\n", $stmt->affected_rows);

	$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);

	$strName = "Weerachai Nukitram";
	$strEmail = "[email protected]";
	$strCountryCode = "TH";
	$strBudget = "6000000";
	$strUsed = "100000";

	$strCustomerID = "C005";

	$sql = "UPDATE customer SET 
			Name = ? ,
			Email = ? ,
			CountryCode = ? ,
			Budget = ? ,
			Used = ?
			WHERE CustomerID = ? ";
	$stmt = $conn->prepare($sql);
	$stmt->bind_param('sssiis', $strName, $strEmail, $strCountryCode, $strBudget, $strUsed,$strCustomerID); //   s - string, b - blob, i - int, etc

	$stmt ->execute();

	printf("%d Row updated.\n", $stmt->affected_rows);

	$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);

	$strCustomerID = "C005";

	$sql = "DELETE FROM customer
		WHERE CustomerID = ? ";
	$stmt = $conn->prepare($sql);
	$stmt->bind_param('s', $strCustomerID); //   s - string, b - blob, i - int, etc

	$stmt ->execute();

	printf("%d Row deleted.\n", $stmt->affected_rows);

	$conn->close();
?>