Minimal script for inserting date into mysql using bind variables

<?php
/*
CREATE DATABASE talin;
USE talin;
CREATE TABLE t2 (a varchar(8), b date, c int);
*/
  function db_error($action, $error) {
    printf("%s failed: %s\n", $action, $error);
    exit();
  }

  $timestamp = DateTime::createFromFormat('d/m/Y','1/1/2021');
  $iso_date = $timestamp->format('Y-m-d');

  $db = new mysqli('localhost', 'talin', 'talin_password', 'talin');
  if(mysqli_connect_errno())
    db_error('Connect', $db->error);

  $query = "INSERT INTO t1(a, b, c) VALUES(?, ?, ?)";
  $stmt = $db->prepare($query);
  if(!$stmt)
    db_error('Prepare', $db->error);

  $a = 'text';
  $b = $iso_date;
  $c = 0;
  $bound = $stmt->bind_param('ssi', $a, $b, $c);
  if(!$bound)
    db_error('Bind', $db->error);

  $executed = $stmt->execute();
  if(!$executed)
    db_error('Execute', $db->error);
?>