Mysql用户订阅查询失败

Question

我有一个名为socialnetwork的数据库，并有5个表category,post_category,posts,subscribe,user。

我的表结构

 --------      ------------- 
    category      posts 
    --------      ------------ 
    categoryID      postID 
    categoryName     post 
            userID 
            categoryID 

    --------------    ---------------   
    post_category    subscribe 
    ---------------    --------------- 
    postID      subscriberID 
    categoryID     categoryID 

    -------------- 
    usertable 
    -------------- 
    userID 
    userName 

数据的表中的

category table        usertable 
--------------------------    ------------------- 
categoryID  categoryName    userID  userName 
---------------------------    -------------------- 
1    film      1 jijojohn32 
2    television     2 sijojohn         


posts_category table      subscribe table 
------------------      ------------------------- 
postID  categoryID     subscriberID categoryID 
---------------------     ------------------------ 
1   1       1    1 
1   2       1    2  
2   2       2    2     


posts table 
--------------------------------------------------- 
postID  post    userID  categoryID 
-------------------------------------------------- 
1   this post is cool 1   1 
2   demo post   2   2 

用户1可以订阅不同的类别，他可以看到他赞同类别的文章。这就是我想在这里实现的。我有这个查询，但它并没有给我我想要的结果。

USE socialnetwork; 
SELECT socialnetwork.usertable.userName,socialnetwork.posts.post, GROUP_CONCAT(socialnetwork.category.categoryName) as category 
FROM socialnetwork.category 
INNER JOIN subscribe 
ON subscribe.categoryID = category.categoryID 
INNER JOIN posts 
ON posts.categoryID = subscribe.categoryID 
INNER JOIN usertable 
ON usertable.userID = posts.userID 
INNER JOIN socialnetwork.post_category 
ON post_category.postID = posts.postID 

WHERE subscriberID = "1" 
GROUP BY socialnetwork.category.categoryName 

这里的结果我得到

--------------------------------- 
    username  post   category 
    ---------------------------------- 
    jijojohn32 this post is cool film, film 
    sijojohn demo post   television 

结果我想

--------------------------------------------- 
    username  post    category 
    ------------------------------------------- 
    jijojohn32 this post is cool  film,television 
    sijojohn demo post    television 

我想从他订阅的类别后，该用户的用户名发布的文章，以及帖子所在的类别。我的查询出了什么问题？任何想法 ？。谢谢

Answer 1

这里的工作查询。我在表格中做了一些修改。从帖子中删除categoryID。制作了一个名为post_category的新表。

-------------- 
post_category 
------------- 
postID 
categoryID 

这里的查询

SELECT GROUP_CONCAT(category.categoryName) as category , category.categoryID , subscribe.subscriberID , posts.post , 
    usertable.userName 

from category 

INNER JOIN subscribe 
ON subscribe.categoryID = category.categoryID 


INNER JOIN post_category 
ON category.categoryID = post_category.categoryID 

INNER JOIN posts 
ON posts.postID = post_category.postID 

INNER JOIN usertable 
ON usertable.userID = posts.userID 

WHERE subscriberID = 1 
GROUP BY post_category.postID 

Answer 2

您没有通过正确的列汇总。我认为这是你想要的查询：

SELECT ut.userName, p.post, GROUP_CONCAT(c.categoryName) as category 
FROM socialnetwork.category c INNER JOIN 
    subscribe s 
    ON s.categoryID = c.categoryID INNER JOIN 
    posts p 
    ON p.categoryID = s.categoryID INNER JOIN 
    usertable ut 
    ON ut.userID = p.userID INNER JOIN 
    socialnetwork.post_category pc 
    ON pc.postID = p.postID 
WHERE subscriberID = 1 
GROUP BY ut.userName, p.post; 

Answer 3

存在一个冲突

分类表由

Category id and Category Name

后表由

Post id and Corresponding Category Id

除了

Post_Category表由

Post id and Category Id

因此，它被从Posts table采摘，即 第1行 - 仅具有1 category id相关联用它

我建议你删除Category id从Post表

是没有意义的有1和表2把钥匙，而在其他表类似的2个键。

尝试建立主键外键关系。

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