我可以在Postgres中使用來自其他表的彙總數據更新表中的多個字段嗎？

Question

我想出瞭如何一次執行一個字段（請參閱下面的兩個更新查詢）。有沒有辦法在單個查詢中做到這一點？

UPDATE upload_data sd 
SET 
    photo_count = 
    (SELECT sum(photo_count) 
    FROM media_uploads mu 
    WHERE mu.user_id=sd.user_id 
    AND mu.date=current_date 
    GROUP BY mu.user_id); 


UPDATE upload_data sd 
SET 
    video_count = 
    (SELECT sum(video_count) 
    FROM media_uploads mu 
    WHERE mu.user_id=sd.user_id 
    AND date_trunc('month', mu.date)=date_trunc('month', sd.date) 
    GROUP BY mu.user_id); 

Answer 1

我想你可以通過JOIN與UPDATE做到這一點。在postgresql中作爲UPDATE syntax，它會這樣：

UPDATE upload_data sd 
SET sd.photo_count = m.photo_count, 
    sd.video_count = m.video_count 
FROM 
(
    SELECT 
    user_id, 
    sum(photo_count) AS photo_count, 
    SUM(video_count) AS video_count 
    FROM media_uploads 
    WHERE mu.date = current_date 
    GROUP BY user_id 
) AS m 
WHERE m.user_id = sd.user_id;