簡單的數據透視查詢幫助

Question

考慮這個查詢：

SELECT COUNT(*) AS pageviews 
FROM stats_hits 
WHERE pageID='1' AND entrytime>DATE_SUB(now(), INTERVAL 5 DAY) 
GROUP BY DATE(`entrytime`) LIMIT 5 

返回命中計數爲過去的五天裏：是這樣的：

11 
12 
18 
15 
5 

我怎麼可以重寫此查詢返回水平結果集？

11, 12, 18, 15, 5 

謝謝！

編輯：作爲一個側面的問題，沒有人知道如何調整此查詢顯示爲0沒有命中的日子？此刻如果某一天沒有點擊，則只返回4個結果。

Answer 1

SELECT GROUP_CONCAT(s.pageviews) AS pageviews 
FROM 
    (
    SELECT COUNT(*) AS pageviews 
    FROM stats_hits 
    WHERE pageID='1' AND entrytime>DATE_SUB(now(), INTERVAL 5 DAY) 
    GROUP BY DATE(`entrytime`) LIMIT 5 
) s; 

參見：http://dev.mysql.com/doc/refman/5.1/en/group-by-functions.html#function_group-concat

如果你想永遠有5個結果，這樣的事情醜陋的黑客攻擊可能會奏效。

SELECT GROUP_CONCAT(s2.pageviews) AS pageviews 
FROM 
    (
    SELECT * FROM 
    (
    SELECT COUNT(*) AS pageviews 
    FROM stats_hits 
    WHERE pageID='1' AND entrytime>DATE_SUB(now(), INTERVAL 5 DAY) 
    GROUP BY DATE(`entrytime`) LIMIT 5 
    UNION ALL SELECT 0 AS pageviews 
    UNION ALL SELECT 0 AS pageviews 
    UNION ALL SELECT 0 AS pageviews 
    UNION ALL SELECT 0 AS pageviews 
    UNION ALL SELECT 0 AS pageviews 
    ) s1 
    ORDER BY pageviews = 0 ASC 
    LIMIT 5) s2; 

另一種選擇是這

CREATE TEMPORARY TABLE temp_table LIKE SELECT 0 as pageviews; 
INSERT INTO temp_table VALUES (0),(0),(0),....,(0); 
INSERT INTO temp_table 
    SELECT COUNT(*) AS pageviews 
    FROM stats_hits 
    WHERE pageID='1' AND entrytime>DATE_SUB(now(), INTERVAL x DAY) 
    GROUP BY DATE(`entrytime`) LIMIT x; //replace x with the number of days 

SELECT GROUP_CONCAT(t.pageviews) AS pageviews 
FROM temp_table t 
ORDER BY t.pageview = 0 ASC 
LIMIT x; //replace x with the number of days