How can a beginner effectively learn PHP and SQL in order to build a secure web application?

To effectively learn PHP and SQL as a beginner to build a secure web application, one can start by studying the basics of PHP programming language and SQL database management. It is important to understand how PHP interacts with a database using SQL queries to retrieve, insert, update, and delete data securely. Additionally, learning about best practices for securing web applications, such as input validation, parameterized queries, and using prepared statements, is crucial to prevent SQL injection attacks. 

<?php
// Establish a connection to the database
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// Sample SQL query to retrieve data securely
$user_id = $_GET['user_id'];
$stmt = $conn->prepare("SELECT * FROM users WHERE id = ?");
$stmt->bind_param("i", $user_id);
$stmt->execute();
$result = $stmt->get_result();

while ($row = $result->fetch_assoc()) {
    // Process retrieved data
}

$stmt->close();
$conn->close();
?>

Keywords

PHP SQL web application security beginner

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