How does php and condition works - php

Question

I'm retrieving users from my database with this php code below.
The problem is that when I execute the query without the AND condition, it works fine. With the AND condition it gives me always the else result.
include("config.php");
$con=mysqli_connect($host,$username,$pwd,$db) or die('Unable to connect');
if(mysqli_connect_error($con))
{
echo "Failed to Connect to Database ".mysqli_connect_error();
}
$contact = mysqli_real_escape_string($con, $_GET['contact']);
$password = mysqli_real_escape_string($con, $_GET['motdepasse']);
$sql = "SELECT * FROM bonfoodUtilisateurs WHERE contact = '$contact' AND motdepasse = '$password'";
$result = mysqli_query($con,$sql);
$response = array();
if (mysqli_num_rows($result)!=0) {
$response['code'] = '1';
$response['message'] = 'success message.';
echo json_encode($response);
mysqli_close($con);
}else{
$response['code'] = '2';
$response['message'] = 'error message.';
echo json_encode($response);
mysqli_close($con);
}
?>
I'm expecting to get a result like ```{"code":"2","message":"error message."}
if the user's ```contact and ```password don't exist in the data table
otherwise get ```{"code":"1","message":"success message."}