加入4桌在MySQL中，最大行從一個表

Question

我在MySQL數據庫中的四個表，我試圖創建一個連接所有四個從日誌表拉動的最新數據查詢：

• 評級（ID，等級，設備ID，listingId）
• 數據（listingId，名稱，位置）
• 設備（設備ID，型號）
• 日誌（dateAdded，DEVICEID，appVersion）

我想顯示： 評級，名稱，地點，型號，應用程序版本

應用程序版本隨時間變化，因此它與設備表保持分離。

以下查詢讓我在那裏的一半。問題是appVersion不是最新的。

SELECT ratings.id,ratings.listingId,ratings.rating,data.name,devices.model,tt.appVersion 
FROM ratings 
JOIN data on ratings.listingId = data.id 
JOIN devices on ratings.deviceIdentifier = devices.deviceIdentifier 
JOIN (select max(dateAdded), appVersion, deviceIdentifier from logs) tt 
ORDER BY dateAdded DESC; 

如果我嘗試以下任一語句，查詢將超時。

SELECT ratings.id,ratings.listingId,ratings.rating,data.name,devices.model,tt.appVersion 
FROM ratings 
JOIN data on ratings.listingId = data.id 
JOIN devices on ratings.deviceIdentifier = devices.deviceIdentifier 
JOIN (select max(dateAdded), appVersion, deviceIdentifier from logs where dateAdded in  
(select max(dateAdded) from logs group by deviceIdentifier)) tt 
ORDER BY dateAdded DESC; 

或

SELECT ratings.id,ratings.listingId,ratings.rating,data.name,devices.model,logs.appVersion 
FROM ratings 
JOIN data on ratings.listingId = data.id 
JOIN devices on ratings.deviceIdentifier = devices.deviceIdentifier 
JOIN (select t.deviceIdentifier, t.appVersion 
    from logs t 
    inner join (select deviceIdentifier, max(dateAdded) as dateAdded from logs 
      group by deviceIdentifier) x 
      on t.deviceIdentifier = x.deviceIdentifier and t.dateAdded = x.dateAdded) tt 
ORDER BY dateAdded DESC; 

Answer 1

編輯：修正小bug。我已經測試過這個，它工作。

set @deviceId := 0; 
select * 
from (select r.id, r.listingId, r.rating, data.name, d.model, d.deviceId, l.appVersion 
    FROM ratings r 
    JOIN data on r.listingId = data.listingId 
    JOIN devices d on r.deviceId = d.d eviceId 
    JOIN logs l on l.deviceId = d.deviceId 
    ORDER BY d.deviceId, dateAdded DESC) x 
where @deviceId != deviceId 
and (@deviceId := deviceId) is not null;