Changing A Value in table saving issue - php

Question

This code should check if the row col intersection of LikedOne and the row where username is jim equals text "empty".
$stmt1 = $conn->prepare("SELECT likedOne FROM UserData WHERE username = ?");
$stmt1->bind_param('s',$username);
//$username = $_POST["username"];
$username ="jim";
$stmt1->execute();
$stmt1->store_result();
$res = $stmt1->fetch();
if ( $res == "empty"){
echo "debug 3";
$sql = $conn->prepare("UPDATE UserData SET likedOne=? WHERE username=?");
$sql->bind_param('ss',$TUsername,$Username);
// $TUsername = $_POST["TUsername"];
// $Username = $_POST["username"];
$TUsername = "test";
$Username = "jim";
$sql->execute();
}
The first time it does change it to test but then it still prints debug 3 meaning it it still registering the $res as "empty" even though it should be "test".
Edit that is not working!
$stmt1 = $conn->prepare("SELECT likedOne FROM UserData WHERE username = ?");
$stmt1->bind_param('s',$username);
//$username = $_POST["username"];
$username ="jim";
$stmt1->execute();
$stmt1->bind_result($res);
$found_row = $stmt1->store_result();
if ( $found_row && $res == "empty"){
echo "debug 3";
$sql = $conn->prepare("UPDATE UserData SET likedOne=? WHERE username=?");
$sql->bind_param('ss',$TUsername,$Username);
// $TUsername = $_POST["TUsername"];
// $Username = $_POST["username"];
$TUsername = "test";
$Username = "jim";
$sql->execute();
}

Answer 1

$stmt1->fetch() doesn't return the contents of the likedOne column. It returns TRUE if a row was returned, NULL if there are no more rows in the result set, or FALSE if an error occurred.
To retrieve the data returned by a prepared statement, you need to use $stmt1->bind_result().
$stmt1 = $conn->prepare("SELECT likedOne FROM UserData WHERE username = ?");
$stmt1->bind_param('s',$username);
//$username = $_POST["username"];
$username ="jim";
$stmt1->execute();
$stmt1->bind_result($res);
$found_row = $stmt1->store_result();
if ($found_row && $res == "empty") {
...
}
I'm not sure why your code that does this isn't working, but it's not necessary to do two queries, you can do it in one.
$sql = $conn->prepare("UPDATE UserData SET likedOne=? WHERE username=? AND likedOne = 'empty'");
$sql->bind_param('ss',$TUsername,$Username);
//$TUsername = $_POST["TUsername"];
//$Username = $_POST["username"];
$TUsername = "test";
$Username = "jim";
$sql->execute();