MySQL查詢，USER_ID

Question

我查詢計數出現次數是：

SELECT * FROM (SELECT user_id 
FROM goals 
LEFT JOIN goal_results ON goals.id = goal_results.goal_id 
WHERE goals.enabled = 1 AND validation = 'accepted') AS u 

我的結果是：

| user_id | 
| 4 | 
| 5 | 
| 4 | 
| 5 | 
| 6 | 

我需要讓他們每個人的計數，如：

4> 2

5> 2

6> 1

我已經試過許多類型的查詢與子查詢，或者使用不同的，但我迷路了，我沒有達到我的目標......

任何想法嗎？

Answer 1

您可以使用GROUP BY和COUNT來實現此目的。子查詢不是必需的。

SELECT goal_results.user_id, COUNT(*) qty 
FROM goals 
LEFT JOIN goal_results ON goals.id = goal_results.goal_id 
WHERE goals.enabled = 1 AND goal_results.validation = 'accepted' 
GROUP BY goal_results.user_id 

Answer 2

添加組將由做。

SELECT u.user_id, count(*) FROM (SELECT user_id 
FROM goals 
LEFT JOIN goal_results ON goals.id = goal_results.goal_id 
WHERE goals.enabled = 1 AND validation = 'accepted') AS u 
group by u.user_id 

Answer 3

你不需要使用子查詢做到這一點：

SELECT g.user_id, count(*) 
FROM goals g LEFT JOIN 
    goal_results gr 
    ON g.id = gr.goal_id 
WHERE g.enabled = 1 AND validation = 'accepted' 
GROUP BY g.user_id; 

我的猜測，不過，是你真正想要的：

SELECT g.user_id, count(gr.goal_id) 
FROM goals g LEFT JOIN 
    goal_results gr 
    ON g.id = gr.goal_id 
WHERE g.enabled = 1 AND validation = 'accepted' 
GROUP BY g.user_id; 

這將返回0用戶沒有目標。第一個會爲他們返回1。