How can PHP developers ensure data integrity when retrieving values from a database?

PHP developers can ensure data integrity when retrieving values from a database by using prepared statements with parameterized queries. This helps prevent SQL injection attacks and ensures that the data retrieved is safe and accurate. Additionally, developers should validate and sanitize user input before querying the database to further protect against malicious input. 

// Establish a database connection
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";
$conn = new mysqli($servername, $username, $password, $dbname);

// Prepare a statement with a parameterized query
$stmt = $conn->prepare("SELECT * FROM users WHERE username = ?");
$stmt->bind_param("s", $username);

// Sanitize and validate user input
$username = filter_var($_POST['username'], FILTER_SANITIZE_STRING);

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

// Get the result set
$result = $stmt->get_result();

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

// Close the statement and connection
$stmt->close();
$conn->close();

Keywords

SQL injection PDO prepared statements data validation error handling

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