php - 数组中的值未编入索引

Question

该脚本应从数据库中选择 StaffID，然后将其放入一个数组中，然后我可以从那里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

'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：未定义索引：E:\EasyPHP-12.1\www\Placing_Orders.php 112 行中的staffID

为什么是这样？

Answer 1

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

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