How can outdated PHP functions like mysql_real_escape_string impact checkbox functionality?

Using outdated PHP functions like mysql_real_escape_string can impact checkbox functionality by not properly sanitizing user input, leading to potential SQL injection vulnerabilities. To solve this issue, it is recommended to use parameterized queries or the mysqli_real_escape_string function for sanitizing user input.

// Example of using mysqli_real_escape_string to sanitize input for checkboxes
$checkbox_value = isset($_POST['checkbox']) ? mysqli_real_escape_string($connection, $_POST['checkbox']) : '';