破坏的文件图标从数据库php和mysql检索图像

我需要从数据库上传和检索图片，我可以将图片存储在数据库中，但无法在以后显示。请帮助
我写了以下代码从数据库中检索。

I need to upload and retrieve image from a database, I am able to store the image in the database but unable to display it later. please help I wrote the following code to retrieve from the database.

  $result1=mysql_query("INSERT INTO userdata(id, username, firstname, lastname, imageType, image)VALUES('', '" . $_SESSION['username'] . "', '" . $_SESSION['firstname'] . "', '$lastname','{$image_size['mime']}','{$imgData}')") or die("Invalid query: " . mysql_error());
if($result1)
{
echo "</br>";
echo "Registration successful";
echo "</br>";
echo $lastid=mysql_insert_id();//get the id of the last record
echo "uploaded image is :"; ?>
<img src="imageView.php?image_id=<?php echo $lastid; ?>" /><br/>

<?php
echo "</br>";     
}#if result1into db successful
else 
{
echo $result1;
echo "Problem in database operation";

imageView.php具有以下代码：

imageView.php has the following code:

    <?php
    $conn = mysql_connect("localhost", "root", "");
    mysql_select_db("wordgraphic") or die(mysql_error());
         if(isset($_GET['id'])) {
        $sql = "SELECT imageType,image FROM userdata WHERE id=". $_GET['image_id'];
        $result = mysql_query("$sql") or die("<b>Error:</b> Problem on Retrieving Image BLOB<br/>" . mysql_error());
        $row = mysql_fetch_array($result);
        header("Content-type: " . $row["imageType"]);
        echo $row["image"];
         }
    mysql_close($conn);
?>

代码可能有什么错误？
当我尝试运行 imageView.php 与静态id图像正在显示。所以我猜错误传递的变量是这个代码：

What could be possibly wrong with the code? When i try to run imageView.php with static id image is getting displayed. So i guess the error is in passing the variable is this code:

 echo "uploaded image is :"; ?>
<img src="imageView.php?image_id=<?php echo $lastid; ?>" /><br/>
<?php

什么可能会出错？