路口與MySQL與查詢

我想相交2個querys在MySQL以這種方式：路口與MySQL與查詢

SELECT user_id FROM post GROUP BY thread_id HAVING COUNT(thread_id) = 1 
INTERSECT 
SELECT user_id FROM post GROUP BY user_id HAVING COUNT(user_id) = 1;

我已經看了各種方法來做到這一點在MySQL，但不幸的是使用IN和INNER JOIN還沒有爲我工作。

測試數據我工作是：

insert into post (post_number, timestamp, user_id, thread_id) values(0,0,1,1000); 
insert into post (post_number, timestamp, user_id, thread_id) values(0,0,2,2000); 
insert into post (post_number, timestamp, user_id, thread_id) values(0,0,3,2000); 
insert into post (post_number, timestamp, user_id, thread_id) values(0,0,4,3000); 
insert into post (post_number, timestamp, user_id, thread_id) values(0,0,5,4000); 
insert into post (post_number, timestamp, user_id, thread_id) values(0,0,1,4000);

運行我的兩個查詢的交集應該導致

任何幫助表示讚賞，感謝。

來源

2011-09-01 nehalpatels

當你運行你的查詢您能得到什麼？ –

你的交集的第一部分是無效的sql：你不能選擇你沒有分組的東西。這在MySql中有效嗎？你在第一個陳述中表達了什麼概念？它是否選擇僅在一個線程中發佈的用戶？用戶是線程中唯一的海報？ – jkebinger

所以，你想要發佈一個孤兒線程的用戶列表？也許子選擇效果最好。

SELECT user_id 
    FROM (
    SELECT user_id 
     FROM post 
     GROUP BY thread_id 
     HAVING COUNT(thread_id) = 1 
) AS orphan 
    GROUP BY user_id 
    HAVING COUNT(user_id) = 1

編輯：是的，上面是錯誤的;我沒有足夠的考慮。下面是另一個去，但不要讓你的希望：

SELECT user_id 
    FROM (
    SELECT user_id 
     FROM post 
     GROUP BY thread_id 
     HAVING COUNT(thread_id) = 1 
) AS orphan_post 
    INNER JOIN (
    SELECT user_id 
     FROM post 
     GROUP BY user_id 
     HAVING COUNT(user_id) = 1 
) AS orphan_user 
    ON user_id

來源

2011-09-01 20:59:59 Neil

Postgres裏我會做這樣的

SELECT user_id FROM post where thread_id in (
select thread_id from post group by thread_id having count(distinct user_id) = 1) 
INTERSECT 
SELECT user_id FROM post GROUP BY user_id HAVING COUNT(user_id) = 1;

然而，顯然MySQL不支持交叉，所以內連接就足夠了：

SELECT post.user_id FROM post 
join (SELECT user_id FROM post GROUP BY user_id HAVING COUNT(user_id) = 1) x on x.user_id = post.user_id 
where 
post.thread_id in (
select thread_id from post group by thread_id having count(distinct user_id) = 1)

這些都返回4

來源

2011-09-02 11:42:37 jkebinger

路口與MySQL與查詢

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