update picture into database table using php - php

Question

I have an address table and one of the fields is an image blob. When I update a record through $POST and include an image, everything works. However if no image is included in $POST, I want to reuse the image that is already stored in the record. This is were im having problems. when I run the code below it does not update the image file. here's my code.
function UpdateRecordfromPost()
{
if ($_SERVER["REQUEST_METHOD"] == "POST")
{
$FirstName = test_input($_POST['fname']);
$LastName = test_input($_POST['lname']);
$Address = test_input($_POST['address']);
$Town = test_input($_POST['town']);
$Postcode = test_input($_POST['pcode']);
$Phone = test_input($_POST['phone']);
$Email = test_input($_POST['email']);
$ID = ($_POST['idname']);
}
$mysqli = new mysqli( $GLOBALS['servername'], $GLOBALS['username'], $GLOBALS['password'], $GLOBALS['dbname']);
if ($mysqli->connect_error)
{
die("Connection failed: " . $mysqli->connect_error);
}
$image = GetimagefromPost(); //this function returns a image and seems to work
if ($image == "")
{
$image = Saveimaqgefile($ID);
}
$query = "UPDATE addressbook SET firstname='$FirstName',lastname='$LastName',street='$Address',town='$Town',PostCode='$Postcode',phone='$Phone',email='$Email',Photo='$image' WHERE id='$ID'";
if ($result = $mysqli->query($query))
{
echo "Updated record successfully";
}
else
{
echo "Error: " . $query . "<br>" . $mysqli->error;
}
$mysqli->close();
}
function Saveimaqgefile($file_id) {
$mysqli = new mysqli( $GLOBALS['servername'], $GLOBALS['username'], $GLOBALS['password'], $GLOBALS['dbname']);
if ($mysqli->connect_error)
{
die("Connection failed: " . $conn->connect_error);
}
$sql= "SELECT * from ".$GLOBALS['dbname']. " WHERE id=".$file_id;
$result = $mysqli->query($sql);
if ($result->num_rows > 0)
{
$row=mysqli_fetch_array($result);
}
else { $row = "";}
$mysqli->close();
return base64_encode($row['Photo']);
}
This is my first question, sorry if i've done something wrong

Answer 1

You'd need conditional logic.
if (image was uploaded) {
mysqli_query('... update record with new image ...;);
} else {
mysqli_query('... update record WITHOUT image data ...');
}
For most other types of (small) data, you could do it in a single query, e.g.
UPDATE ... SET field=IF($newdata = '', field, $newdata)
but your image blob is likely to be HUGE, and you don't want to repeat it twice in the same query string.