將SQL查詢與共享邏輯結合

我目前正在複製一個相當大的SQL聚合查詢，以便我可以運行一次以返回整個數據集的度量標準，然後再對每天的度量標準進行分組。將SQL查詢與共享邏輯結合

下面是計算總體指標的查詢的簡化示例。

SELECT 
    sum(sentiment) FILTER (WHERE user = :user) AS total_sentiment, 
    avg(sentiment) FILTER (WHERE user = :user) AS average_sentiment, 
    count(messages) FILTER (WHERE sender = :user) AS total_messages 
FROM 
    "Messages" 
WHERE 
    date >= :start AND date < :end;

而這裏是計算相同指標的計算方法，但每天計算一次。

SELECT 
    date_trunc('day', date) AS date, 
    sum(sentiment) FILTER (WHERE user = :user) AS total_sentiment, 
    avg(sentiment) FILTER (WHERE user = :user) AS average_sentiment, 
    count(messages) FILTER (WHERE sender = :user) AS total_messages 
FROM 
    "Messages" 
WHERE 
    date >= :start AND date < :end; 
GROUP BY 1 
ORDER BY 1

有沒有辦法結合這兩個查詢，而不必重複大多數的邏輯？

以編程方式構建查詢字符串是一個選項，但我絕對不會沿着那條路徑走。

如果查詢實際上和上面的例子一樣簡單，那麼重複它們並不是一個問題，但它們處理更復雜的連接和統計功能 - 保持它們同步已經非常棘手。

理想情況下，輸出將是一個表，其第一行包含整體指標，其餘行將是每日計算。

來源

2017-08-08 Dan Prince

最簡單的方法是使用grouping sets：

SELECT date_trunc('day', date) AS date, 
     sum(sentiment) FILTER (WHERE user = :user) AS total_sentiment, 
     avg(sentiment) FILTER (WHERE user = :user) AS average_sentiment, 
     count(messages) FILTER (WHERE sender = :user) AS total_messages 
FROM "Messages" 
WHERE date >= :start AND date < :end 
GROUP BY GROUPING SETS ((), (date));

來源

2017-08-08 12:37:30

你可以使用窗口功能：

SELECT DISTINCT 
    date_trunc('day', date) AS date, 
    sum(sentiment) FILTER (WHERE user = :user) OVER() AS total_sentiment, 
    avg(sentiment) FILTER (WHERE user = :user) OVER() AS average_sentiment, 
    count(messages) FILTER (WHERE sender = :user) OVER() AS total_messages, 
    sum(sentiment) FILTER (WHERE user = :user) OVER(PARTITION BY date_trunc('day', date)) 
    AS total_sentiment_per_day, 
    ... 
FROM "Messages" 
WHERE date >= :start AND date < :end; 
ORDER BY 1

來源

2017-08-08 12:37:56 lad2025

將SQL查詢與共享邏輯結合

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