What are some best practices for handling user input in SQL queries to prevent SQL injection vulnerabilities in PHP?

SQL injection vulnerabilities occur when user input is not properly sanitized before being included in SQL queries, allowing attackers to manipulate the query and potentially access or modify the database. To prevent SQL injection, it is important to use prepared statements with parameterized queries in PHP, which separate the SQL code from the user input. 

// Establish a database connection
$pdo = new PDO('mysql:host=localhost;dbname=mydatabase', 'username', 'password');

// Prepare a SQL statement with a parameterized query
$stmt = $pdo->prepare('SELECT * FROM users WHERE username = :username');

// Bind the user input to the parameter in the query
$stmt->bindParam(':username', $_POST['username']);

// Execute the query
$stmt->execute();

// Fetch the results
$results = $stmt->fetchAll();

Keywords

SQL injection user input validation prepared statements parameterized queries PDO

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