表单重新提交 - 更新Mysql记录 - PHP PDo语句

I have an HTML5 form. When Users submitting the form with their unique user id's the data will be stored in the mysql database. I have already stored their user id's in the database. My problem is to when Iam trying to submit the form the form data won't be updated in the database. Can you help me at this moment with the help of php PDO statements.

Your PDO update syntax should be like this.

Example:

If you want to update user status from "NOVICE" to "EXPERT"

$id = $_POST['id'];
$status = $_POST['newstatus']; // newstatus = expert

$sql = "UPDATE databse_name SET status-field = ? WHERE user_ID_field = ?";
        $statement = $con_db->prepare($sql);
        $statement->execute(array($status, $id));