SQL获取查询中所有用户活动的总和

Question

I want get all users from users table and have a column summed up on all articles length written by all users from article table

Basically Here is a code if I choose to run an SQL query for each loop (not good)

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

I have used LEFT JOIN but I can only get a list of users with their user_id present on article table

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 

With this query, I only get users with their user_id present in the article table but I want all users listed and NULL/empty returned if the user has no article with his/her id present

Answer 1

You need 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