数组中的值未编入索引

Question

此脚本应从数据库中选择StaffID，然后将其放入一个数组中，然后从那里我可以将其放入一个变量中，以便在下一个查询中使用。

$query  = "SELECT StaffID FROM staff WHERE First_Name = '$db_staff_member_first_name' AND Last_Name = '$db_staff_member_last_name'";
    $result = mysql_query($query)
    or die(mysql_error());
    echo $result;
    echo $query + "<br>";
    while($row = mysql_fetch_array($result, MYSQL_ASSOC))
    {
$db_staffid = $row['staffID'];
}

脚本运行后我得到了

'Resource id #4SELECT CustomerID FROM customer WHERE Customer_First_Name = 'Christopher' AND Customer_Last_Name = 'Bennett'Resource id #50'

然后是以下通知：

  

注意：未定义的索引：staffID in   第112行的E：\ EasyPHP-12.1 \ www \ Placing_Orders.php

为什么会这样？

Answer 1

http://php.net/manual/en/function.mysql-fetch-array.php

Note: Field names returned by this function are case-sensitive.