MySQL - 單個SQL查詢中的總計數和更改率

Question

我試圖提取網站點擊總數加上每個客戶端每個城市每天的更改率（增加/減少率）一個單一的SQL查詢，但無法做到正確。

我創建的

http://www.sqlfiddle.com/#!9/fd279/8

一個例子，我能請請求援助？

Answer 1

嘗試避免內部聯接，它有錯誤的情況呢（t1.hitDate = t2.hitDate and t1.hitDate-1 = t2.hitDate不能滿足）：

select 
    t1.HitDate, 
    t1.City, 
    t1.Client, 
    SUM(t1.NumVisits) - IFNULL((SELECT SUM(t2.NumVisits) FROM PAGE_HITS t2 WHERE t2.HitDate = t1.HitDate-1 AND t2.City = t1.City AND t2.Client = t1.Client), 0) as rate_of_change 
from 
    PAGE_HITS t1 
WHERE 
t1.Client='C' 
group by 
    HitDate, 
    City 
    ORDER BY HitDate; 

Answer 2

要獲得基於百分比增加/減少

select 
    t1.HitDate, 
    t1.City, 
    t1.Client, 
    SUM(t1.NumVisits), 
    IFNULL(((SUM(t1.NumVisits) - IFNULL((SELECT SUM(t2.NumVisits) FROM PAGE_HITS t2 WHERE t2.HitDate = t1.HitDate-1 AND t2.City = t1.City AND t2.Client = t1.Client), 0)) * 100)/IFNULL((SELECT SUM(t2.NumVisits) FROM PAGE_HITS t2 WHERE t2.HitDate = t1.HitDate-1 AND t2.City = t1.City AND t2.Client = t1.Client), 0),0) as rate_of_change 
from 
    PAGE_HITS t1 
WHERE 
t1.Client='C' 
group by 
    HitDate, 
    City 
    ORDER BY HitDate; 

Answer 3

先做一個唯一編號像rownum 並作出相同的查詢 和加入rownum列 然後你可以看到前一個月作爲新列和計算變化率。

SELECT A.HitDate, A.City, A.sumThis, B.sumFormer, (A.sumThis/B.sumFormer - 1) * 100 as 'ChangingRate' 
From (
     select @rownum1:=@rownum1 + 1 as 'rownum1', HitDate, City, sum(NumVisits) as 'sumThis' 
     from page_hits, (Select @rownum1:=0) R 
     Where client = 'C' 
     Group by HitDate, City 
     ) A 
Left Join (
     select @rownum2:=@rownum2 + 1 as 'rownum2', HitDate, City, sum(NumVisits) as 'sumFormer' 
     from page_hits, (Select @rownum2:=0) R 
     Where client = 'C' 
     Group by HitDate, City 
     ) B On A.rownum1 - 1 = B.rownum2