我正在尝试学习将图像插入到***phpmyadmin***my db structer中：

id int(11) AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(255),
mime VARCHAR(255),
data BLOB

我代码是：

<?php
        ini_set('display_errors', '1');
        ini_set('display_startup_errors', '1');
        error_reporting(E_ALL);
        $dbh = new PDO("mysql:host=localhost;dbname=mydata", "root", "123456");

        if(isset($_POST['btn'])){
            $name = $_FILES['myfile']['name'];
            $type = $_FILES['myfile']['type'];
            $data = file_get_contents($_FILES['myfile']['tmp_name']);
            $stmt = $dbh->prepare("INSERT INTO myblob VALUES('',?,?,?)");
            $stmt->bindParam(1,$name);
            $stmt->bindParam(2,$type);
            $stmt->bindParam(3,$data);
            $stmt->execute();
        }
        ?>
        <form method="post" enctype="multipart/form-data">
            <input type="file" name="myfile" />
            <button name="btn">Upload</button>
        </form>

我提交错误：

Uncaught PDOException: SQLSTATE[22007]: Invalid datetime format: 1366 Incorrect integer value: '' for column `mydata`.`myblob`.`id` at row 1

有什么想法是错误的，当试图上传一个png文件？