php - 无法从查询中获取值

Question

我正在运行下面的代码，但它返回一个错误:"undefined index: value"

$two_tier= mysql_query("
    SELECT Count(1)
    FROM(
        SELECT `login_id`
        FROM `data`
        WHERE Year(`start_at`) = Year(Date_sub(Now(), INTERVAL 1 month))
        AND Month(`start_at`) = Month(Date_sub(Now(), INTERVAL 1 month)) 
        AND end_at > Date_add(start_at, INTERVAL 5 minute) 
        GROUP  BY `login_id`
        HAVING Count(`login_id`) > 1
    ) AS Value
");

$two_cnt = mysql_fetch_assoc($two_tier);
echo $two_cnt['value'];

我正在尝试获取“值”。请提供一点帮助。

Answer 1

SELECT Count(1) as my_value
FROM   (SELECT `login_id` 
        FROM   `data` 
        WHERE  ( Year(`start_at`) = Year(Date_sub(Now(), INTERVAL 1 month)) 
                 AND Month(`start_at`) = Month(Date_sub(Now(), INTERVAL 1 month) 
                                         ) ) 
               AND ( end_at > Date_add(start_at, INTERVAL 5 minute) ) 
        GROUP  BY `login_id` 
        HAVING Count(`login_id`) > 1) AS Value


$two_cnt = mysql_fetch_assoc($two_tier);
echo $two_cnt['my_value'];

你选择你的 FROM 作为 Value，但是第一次选择的结果不在那个 Value 中，你还需要一个 AS