引用来自php的图像

I have a function on a website where I have a img reference leading to a php page

<img src="selectimage.php?uid=21312412">

which I need to return an image and update a database file

<?php
$servername = "localhost";
$username = "webz";
$password = "BLAH";
$dbname = "contactlist";
$readid = $_GET["uid"];
$conn = new mysqli($servername, $username, $password, $dbname);
$sql = "UPDATE emails SET `read`='1' WHERE `id`='" .$readid. "'";
if ($conn->query($sql) === TRUE) {
echo "<img src='logo11w.png'>";
}

$conn->close();
?>

I figured this would not work as I am referencing a php page in which is referencing the HTML tag

While this is updating my database it is not displaying the image.

how do I make this php file send the image logo11w.png to that img tag

Further note : include or other methods of including this code on the page loading are out of the question because this procedure may be called from a off-server source.

The most effective method for what I am trying to do turns out to be:

...

if ($conn->query($sql) === TRUE) {
header('Content-Type: image/jpeg');
echo file_get_contents('https://www.google.com/images/srpr/logo11w.png'); 
} else {
echo "Error updating record: " . $conn->error;
}

...

Store user id in one hidden field
You can use ajax for get respone back from php page after updating value in database

<input type="hidden" id="userid" value="user_id_value">
<input type="button" id="getimage" value="GET IMAGE">
<div id="u_img"></div>
$(document).ready(function(){
    $('#getimage').click(function() {
        var uid = $('#userid').val();
        var datastring = "uid="+uid;
        $.ajax({
            type: "POST",
            url: "php_page.php",
            data: datastring,
            cache: false,
            success: function(result) {
                $('#u_img').append(result);
            }
        });
    });
});