沒能獲得價值進行查詢

Question

的我正在這下面的代碼，但它返回一個錯誤："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']; 

我試圖讓「價值」。請幫忙。

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']; 

您選擇從作爲價值，而是首先選擇的結果是不是該值，則需要多一個AS

Answer 2

由於SELECT聲明SELECT Count(1)外觀最大的價值，所以你實際上是取Count(1)爲Count(1)，而不是value。要獲取它的價值，你需要這樣做：

SELECT Count(1) AS value .... 

然後代碼將正常工作。所以，最後的聲明將是：

$two_tier= mysql_query(" 
    SELECT Count(1) AS 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 
");