Not checking for User if existing - php

Question

I want to check if a user exists or not.
It keeps registering users even though I added a check inside. The echo does not give me a accurate feedback on how to fix this issue.
Edit:
Code edited due to comments. It does not exit or check for the existing user.
Here is my code:
if($_POST['username']) {
if ( $password == $c_password ) {
$db_name = '*';
$db_user = '*';
$db_password = '*';
$server_url = '*';
$mysqli = new mysqli($server_url , $db_user, $db_password, $db_name);
/* check connection */
if (mysqli_connect_errno()) {
error_log("Connect failed: " . mysqli_connect_error());
echo '{"success":0,"error_message":"' . mysqli_connect_error() . '"}';
} else {
$check="SELECT * FROM USER WHERE 'Name'='". $username."'";
$rs = mysqli_query($mysqli,$check) or die(mysqli_error($mysqli));
$data = mysqli_fetch_array($rs, MYSQLI_NUM);
if($data[0] > 1) {
echo "User Already in Exists<br/>";
exit;
}
else
{
$stmt = $mysqli->prepare("INSERT INTO USER (Name, Password) VALUES (?, ?)");
$password = md5($password);
$stmt->bind_param('ss', $username, $password);
/* execute prepared statement */
$stmt->execute();
if ($stmt->error) {error_log("Error: " . $stmt->error); }
$success = $stmt->affected_rows;
/* close statement and connection */
$stmt->close();
/* close connection */
$mysqli->close();
error_log("Success: $success");
if ($success > 0) {
error_log("User '$username' created.");
echo '{"success":1}';
} else {
echo '{"success":0,"error_message":"Username Exist."}';
}}
}
} else {
echo '{"success":0,"error_message":"Passwords does not match."}';
}
} else {
echo '{"success":0,"error_message":"Invalid Username."}';
}