Check if email and username exist in PHP and mysqli - php

Question

I'm trying to check if a handle or email exists for the riegistration on my mock Twitter project I'm doing called bleeter, but I'm getting this error:
Notice: Object of class mysqli_result could not be converted to int in first.php on line 20
This is the line where I check if num_rows_handle == 0. How am I supposed to do this?
$query_check_handle = "SELECT * FROM users WHERE handle = " . $handle;
$num_rows_handle = mysqli_query($dbc, $query_check_handle);
if ($num_rows_handle == 0) { // Line 20
//check email
$query_check_email = "SELECT * FROM users WHERE email = " . $email;
$num_rows_email = mysqli_query($dbc, $query_check_email);
if ($num_rows_email == 0) {
$query_register = "INSERT INTO users (first_name, last_name, handle, password, email, ACL)
VALUES ('$fname', '$lname', '$handle', '$pass', '$email', '$ACL')"
or DIE ("error running the query.");
mysqli_query($dbc, $query_register);
echo "<br>";
echo "You have succesfully registered, please login";
} else {
echo "<br>";
echo "Email already in use. Please try again";
}
} else {
echo "<br>";
echo "Handle already in use. Please try again";
}

Answer 1

When the query is SELECT, mysqli_query returns the object of type mysqli_result, which has property num_rows containing the number of rows. Thus
$result = mysqli_query($dbc, $query_check_email);
$num_rows_email = mysqli_num_rows($result);