SELECT返回mysqli_num_rows给出错误：类mysqli_result的对象无法转换为字符串

I have the following function. It's aim is to check the database users and see if the email is present in the email column.

If it is present, it should give me a result of int 1 using mysqli_num_rows which I'll use to show the user an error, (sorry, your email is already registered).

If it isn't present, then mysqli_num_rows should return int 0 and the code can continue.

My problem is with this assigning of the SELECT result.

function checkEmail($email,$name){
    // Connects to DB
    $con = connectDB();

    // Creates the SQL to be run
    $sql = "SELECT email FROM `users` WHERE email = '" . $email . "'";

    // Runs the query
    $emailExists = mysqli_query($con,$sql);

    // Uses mysqli_num_rows to return the number of rows with the query
    $num_rows = mysqli_num_rows($emailExists);
    var_dump($num_rows);

    // if no email exists in column
    if ($num_rows == 0){
        // return this to be used elsewhere
        return $emailExists;
    }else{
        // send to error page and halt script
        Header('Location:error.php?error=emailexists&name=' . $name);
        return false;
    }
    mysqli_close($con);
}

But when I run this far, I get this error:

Object of class mysqli_result could not be converted to string

$emailExists is a mysqli_result object

When you use it elsewhere, you are expecting it to be a string. Try doing

return mysqli_fetch_array($emailExists); 

instead of

return $emailExists;

This will return an array, so to access the record you want to use $returnedvalue[0]['column_name'] to access your data