UPDATE SQL with Session - php

Question

I am trying to insert image path into an existing databse. The code below works, but inserts a new row.
$address= htmlentities($_SESSION['address']);
$city= htmlentities($_SESSION['city']);
$zip_code= htmlentities($_SESSION['zip_code']);
$query =
"INSERT INTO property(name, size, type_picture, file_path, username) VALUES (?,?,?,?,?)";
$conn = $db->prepare($query);
if ($conn == TRUE) {
$conn->bind_param("sisss", $myfile, $fileSize, $fileType, $path, $username);
if (!$conn->execute()) {
echo 'error insert';
}else {
echo 'Success!<br/>';
echo '<img src="' . DISPLAY_PATH . $myfile . '"/>';
}
} else {
die("Error preparing Statement");
When I try the same as above but UPDATE, i get the "Error preparing Statement". I need to update empty cells (if this matters).
$query =
"UPDATE property(name, size, type_picture, file_path, username)
SET(?,?,?,?,?)
WHERE address = '$address' // with or without ''
city = '$city' ";
$conn = $db->prepare($query);
if ($conn == TRUE) {
$conn->bind_param("sisss", $myfile, $fileSize, $fileType, $path, $username);
if (!$conn->execute()) {
echo 'error insert';
} // etc. etc.
Thank you so much. Tried for a day, need some help.

Answer 1

Your update query is wrong, try this instead:
$query = "UPDATE property SET name = ?, size = ?, type_picture = ?, file_path = ?, username = ?
WHERE address = ? AND city = ?"
$conn = $db->prepare($query);
if ($conn == TRUE) {
$conn->bind_param("sisss", $myfile, $fileSize, $fileType, $path, $username,$address,$city);
if (!$conn->execute()) {
echo 'error update';
}
}

Answer 2

You need an AND or OR in the WHERE statement:
WHERE address = '$address' AND // with our without ''
city = '$city' ";
I also don't think you should mix parameters with string substitution. Make $address and $city parameters as well.