What are common pitfalls to avoid when querying a database to verify input data in PHP applications?

Common pitfalls to avoid when querying a database to verify input data in PHP applications include not sanitizing user input, not using prepared statements to prevent SQL injection attacks, and not validating input data before querying the database. To solve these issues, always sanitize user input using functions like mysqli_real_escape_string(), use prepared statements with placeholders for input data, and validate input data using filters or regular expressions before querying the database. 

// Sanitize user input
$input_data = mysqli_real_escape_string($conn, $_POST['input_data']);

// Prepare a SQL statement with a placeholder
$stmt = $conn->prepare("SELECT * FROM table WHERE column = ?");
$stmt->bind_param("s", $input_data);
$stmt->execute();

// Validate input data before querying the database
if (filter_var($input_data, FILTER_VALIDATE_EMAIL)) {
    // Query the database
    $result = $stmt->get_result();
    // Process the result
}

Keywords

SQL injection prepared statements PDO data validation input sanitization

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