How to prepare statement for update query?

Question

I have a mysqli query with the following code:

$db_usag->query("UPDATE Applicant SET phone_number ='$phone_number', 
street_name='$street_name', city='$city', county='$county', zip_code='$zip_code', day_date='$day_date', month_date='$month_date',
 year_date='$year_date' WHERE account_id='$account_id'");

However all the data is extracted from HTML documents so to avoid errors I would like to use a prepared statement. I found PHP documentation on bind_param() but there is no UPDATE example.

Solution

An UPDATE works the same as an insert or select. Just replace all the variables with ?.

$sql = "UPDATE Applicant SET phone_number=?, street_name=?, city=?, county=?, zip_code=?, day_date=?, month_date=?, year_date=? WHERE account_id=?";

$stmt = $db_usag->prepare($sql);

// This assumes the date and account_id parameters are integers `d` and the rest are strings `s`
// So that's 5 consecutive string params and then 4 integer params

$stmt->bind_param('sssssdddd', $phone_number, $street_name, $city, $county, $zip_code, $day_date, $month_date, $year_date, $account_id);
$stmt->execute();

if ($stmt->error) {
  echo "FAILURE!!! " . $stmt->error;
}
else echo "Updated {$stmt->affected_rows} rows";

$stmt->close();