查詢失敗，如果沒有行

Question

我有以下查詢返回NULL爲每個字段如果沒有匹配的問題或答案的用戶。請你能告訴我如何防止這種情況發生？

謝謝！

SELECT u.id, u.first_name, u.last_name, u.email, u.username, COUNT(DISTINCT q.id) AS `q_count` , COUNT(DISTINCT a.id) AS `a_count` 
FROM `users` AS u 
INNER JOIN `questions` AS q ON u.id = q.uid 
INNER JOIN `answers` AS a ON u.id = a.uid 
WHERE u.username = 'max' 
LIMIT 0 , 30 

Answer 1

使用left join S的inner join小號

代替