How can SQL injection vulnerabilities be avoided when constructing dynamic SQL queries in PHP?

SQL injection vulnerabilities can be avoided when constructing dynamic SQL queries in PHP by using prepared statements with parameterized queries. This approach separates the SQL query logic from the user input, preventing malicious input from being executed as SQL code. 

// 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 parameter value
$stmt->bindParam(':username', $_POST['username']);

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

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

Keywords

SQL injection dynamic SQL queries prepared statements PDO security

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