SQL獲取查詢中所有用戶活動的總和

Question

我想從用戶表中獲取所有用戶，並在文章表中匯總所有用戶寫的所有文章長度的列

基本上這是一個代碼，如果我選擇為每個循環運行一個SQL查詢（不好）

SELECT * FROM users
--loop
SELECT SUM(wordcount) AS totalwordcount FROM articles WHERE writer_id = user_id

我已經使用了LEFT JOIN，但是我只能在商品表中獲得帶有user_id的用戶列表

SELECT users.name, SUM(article.wordcount) AS xox FROM users LEFT JOIN article ON users.id_usera = article.writer_id WHERE article.editor_status = 'finished' ORDER BY users.id_usera 

通過此查詢，我只獲得在文章表中存在其user_id的用戶，但我希望列出所有用戶，如果該用戶沒有在其ID中存在的文章，則返回NULL /空

Answer 1

您需要GROUP BY ：

SELECT u.name, SUM(a.wordcount) AS xox
FROM users u LEFT JOIN
     article a
     ON u.id_usera = a.writer_id AND
        a.editor_status = 'finished' 
GROUP BY u.name;

Answer 2

SELECT users.name, SUM(article.wordcount) AS TotalWordCount 
FROM users 
LEFT JOIN article ON users.id_usera = article.writer_id 
WHERE article.editor_status = 'finished' 
GROUP BY article.writer_id
ORDER BY users.id_usera