Php SQL从三个表中选择，并在投票系统中排序_Php_Mysql_Sql_Laravel_Join

Php SQL从三个表中选择，并在投票系统中排序

php mysql sql laravel join

Php SQL从三个表中选择，并在投票系统中排序,php,mysql,sql,laravel,join,Php,Mysql,Sql,Laravel,Join,在我的laravel项目中，我有一个投票系统，每个帖子都有很多答案，每个答案都有投票，我试着用投票数的顺序显示帖子的答案。这包括三个表格：帖子：id、标题、内容答案：id、帖子id、内容答案投票：id、帖子id、答案id、用户id、投票（如果还没有人投票支持答案，则为1或0或无）答案投票表中的用户id用于防止用户多次投票。我试图做到这一点： select p.id,a.id,count(*) from posts p, answers a, answer_votes v where

在我的laravel项目中，我有一个投票系统，每个帖子都有很多答案，每个答案都有投票，我试着用投票数的顺序显示帖子的答案。这包括三个表格：

帖子：id、标题、内容

答案：id、帖子id、内容

答案投票：id、帖子id、答案id、用户id、投票（如果还没有人投票支持答案，则为1或0或无）

答案投票表中的用户id用于防止用户多次投票。我试图做到这一点：

select p.id,a.id,count(*) from posts p, answers a, answer_votes v
where  a.id=v.answer_id and p.id=a.post_id and p.id=1 
group by p.id,a.id;

select a.id from answers a, posts b
where a.post_id=1 
and  a.id in (select v.answer_id from answer_votes v where v.vote=1 group by v.answer_id )
or a.id not in (select v.answer_id from answer_votes v where v.answer_id=a.id and v.vote=1 group by v.answer_id );

但它不起作用。。。请帮我解决这个问题

您需要一个内部联接来获取相关表的数据

SELECT p.id
     , p.title
     , p.content
     , a.id
     , a.content
     , SUM(ISNULL(av.vote,0)) AS TotalVotes 
  FROM posts AS p 
 INNER 
  JOIN answers AS a 
    on p.id=a.post_id 
  LEFT 
 OUTER 
  JOIN answer_votes AS av 
    on av.answer_id=a.id 
 GROUP 
    BY p.id
     , p.title
     , p.content
     , a.id
     , a.content 
 ORDER  
    BY TotalVotes

试着这样做：

select p.id,a.id,count(*) from posts p
INNER JOIN answers a ON p.id=a.post_id
INNER JOIN answer_votes v ON a.id=v.answer_id
where  a.id=v.answer_id and p.id=a.post_id and p.id=1 
group by p.id,a.id;

您需要一个内部联接来获取相关表的数据

试着这样做：

select p.id,a.id,count(*) from posts p
INNER JOIN answers a ON p.id=a.post_id
INNER JOIN answer_votes v ON a.id=v.answer_id
where  a.id=v.answer_id and p.id=a.post_id and p.id=1 
group by p.id,a.id;

由于您没有提供任何示例数据，我创建了一些自己的示例数据：

CREATE TABLE posts (id INT, title NVARCHAR(30), content NVARCHAR(200));
CREATE TABLE answers (id INT, post_id INT, content NVARCHAR(200));
CREATE TABLE answer_votes (id INT, post_id INT, answer_id INT, user_id INT, vote bit);

样本数据：

INSERT INTO posts VALUES(1, 'Favorite Color', 'Which is your favorite color?');
INSERT INTO posts VALUES(2, 'Favorite Cheese', 'Which is your favorite cheese?');

INSERT INTO answers VALUES(1, 1, 'Black');
INSERT INTO answers VALUES(2, 1, 'Red');
INSERT INTO answers VALUES(3, 1, 'Yellow');
INSERT INTO answers VALUES(4, 1, 'Green');
INSERT INTO answers VALUES(5, 1, 'Orange');

INSERT INTO answers VALUES(6, 2, 'Parmesan');
INSERT INTO answers VALUES(7, 2, 'Mozarella');
INSERT INTO answers VALUES(8, 2, 'Swiss Cheese');
INSERT INTO answers VALUES(8, 2, 'Colby-Jac');
INSERT INTO answers VALUES(9, 2, 'Monterey Jack');


INSERT INTO answer_votes VALUES(1, 1, 1, 100, 1);
INSERT INTO answer_votes VALUES(2, 1, 2, 101, 1);
INSERT INTO answer_votes VALUES(3, 1, 3, 102, 1);
INSERT INTO answer_votes VALUES(4, 1, 4, 103, 1);
INSERT INTO answer_votes VALUES(5, 1, 5, 104, 1);
INSERT INTO answer_votes VALUES(6, 1, 5, 105, 1);
INSERT INTO answer_votes VALUES(7, 1, 5, 106, 1);
INSERT INTO answer_votes VALUES(8, 1, 3, 107, 1);
INSERT INTO answer_votes VALUES(9, 1, 3, 108, 1);
INSERT INTO answer_votes VALUES(10, 1, 2, 109, 1);
INSERT INTO answer_votes VALUES(11, 1, 2, 110, 1);
INSERT INTO answer_votes VALUES(12, 1, 2, 111, 1);
INSERT INTO answer_votes VALUES(13, 1, 5, 112, 1);
INSERT INTO answer_votes VALUES(14, 1, 5, 113, 1);
INSERT INTO answer_votes VALUES(15, 1, 5, 114, 1);
INSERT INTO answer_votes VALUES(16, 1, 1, 115, 1);

INSERT INTO answer_votes VALUES(17, 2, 6, 100, 1);
INSERT INTO answer_votes VALUES(18, 2, 7, 101, 1);
INSERT INTO answer_votes VALUES(19, 2, 7, 102, 1);
INSERT INTO answer_votes VALUES(20, 2, 7, 103, 1);
INSERT INTO answer_votes VALUES(21, 2, 7, 104, 1);
INSERT INTO answer_votes VALUES(22, 2, 6, 105, 1);
INSERT INTO answer_votes VALUES(23, 2, 6, 106, 1);
INSERT INTO answer_votes VALUES(24, 2, 8, 107, 1);

INSERT INTO answer_votes VALUES(25, 2, 8, 108, 1);
INSERT INTO answer_votes VALUES(26, 2, 9, 109, 1);
INSERT INTO answer_votes VALUES(27, 2, 9, 110, 1);
INSERT INTO answer_votes VALUES(28, 2, 7, 111, 1);
INSERT INTO answer_votes VALUES(29, 2, 7, 112, 1);
INSERT INTO answer_votes VALUES(30, 2, 6, 113, 1);
INSERT INTO answer_votes VALUES(31, 2, 7, 114, 1);
INSERT INTO answer_votes VALUES(32, 2, 8, 115, 1);

您可以使用以下查询：

SELECT      posts.id,
            posts.title,
            posts.content as Question,
            ans.content as Answer,
            COUNT(votes.answer_id) as TotalVotes
FROM        answers ans
INNER JOIN  posts posts on ans.post_id = posts.id
INNER JOIN  answer_votes votes on ans.id = votes.answer_id
WHERE       votes.vote = 1
GROUP BY    votes.answer_id,
            posts.id,
            posts.title,
            posts.content,
            ans.content
ORDER BY    posts.id,
            COUNT(votes.answer_id) DESC

您将看到以下结果集：

id      title                       Question                        Answer          TotalVotes
1     Favorite Color        Which is your favorite color?           Orange              6
1     Favorite Color        Which is your favorite color?           Red                 4
1     Favorite Color        Which is your favorite color?           Yellow              3
1     Favorite Color        Which is your favorite color?           Black               2
1     Favorite Color        Which is your favorite color?           Green               1
2     Favorite Cheese       Which is your favorite cheese?          Mozarella           7
2     Favorite Cheese       Which is your favorite cheese?          Parmesan            4
2     Favorite Cheese       Which is your favorite cheese?          Colby-Jac           3
2     Favorite Cheese       Which is your favorite cheese?          Swiss Cheese        3
2     Favorite Cheese       Which is your favorite cheese?          Monterey Jack       2

你可以在这里看到->

注：这不包括尚未投票的答案

编辑：我知道您希望包含尚未投票的答案。您可以通过如下方式稍微修改上述查询来实现这一点：

SELECT      posts.id,
            posts.title,
            posts.content as Question,
            ans.content as Answer,
            COUNT(votes.answer_id) as TotalVotes

FROM        answers ans
LEFT JOIN   answer_votes votes ON ans.id = votes.answer_id
LEFT JOIN   posts posts ON ans.post_id = posts.id
GROUP BY    posts.id,
            posts.title,
            posts.content,
            ans.content,
            votes.answer_id
ORDER BY    posts.id,
            COUNT(votes.answer_id) DESC

稍微修改上述数据集，如下所示：

INSERT INTO answer_votes VALUES(1, 1, 5, 100, 1)
INSERT INTO answer_votes VALUES(16, 1, 5, 115, 1)

请注意，现在没有人投票支持“黑色”的答案。此查询将生成以下结果集：

id      title                   Question                    Answer      TotalVotes
1   Favorite Color      Which is your favorite color?       Orange          8
1   Favorite Color      Which is your favorite color?       Red             4
1   Favorite Color      Which is your favorite color?       Yellow          3
1   Favorite Color      Which is your favorite color?       Green           1
1   Favorite Color      Which is your favorite color?       Black           0       /* Shows 0 votes for Black */
2   Favorite Cheese     Which is your favorite cheese?      Mozarella       7
2   Favorite Cheese     Which is your favorite cheese?      Parmesan        4
2   Favorite Cheese     Which is your favorite cheese?      Swiss Cheese    3
2   Favorite Cheese     Which is your favorite cheese?      Colby-Jac       3
2   Favorite Cheese     Which is your favorite cheese?      Monterey Jack   2

你可以在这里看到->

希望这有帮助

由于您没有提供任何示例数据，我创建了一些自己的示例数据：

CREATE TABLE posts (id INT, title NVARCHAR(30), content NVARCHAR(200));
CREATE TABLE answers (id INT, post_id INT, content NVARCHAR(200));
CREATE TABLE answer_votes (id INT, post_id INT, answer_id INT, user_id INT, vote bit);

样本数据：

INSERT INTO posts VALUES(1, 'Favorite Color', 'Which is your favorite color?');
INSERT INTO posts VALUES(2, 'Favorite Cheese', 'Which is your favorite cheese?');

INSERT INTO answers VALUES(1, 1, 'Black');
INSERT INTO answers VALUES(2, 1, 'Red');
INSERT INTO answers VALUES(3, 1, 'Yellow');
INSERT INTO answers VALUES(4, 1, 'Green');
INSERT INTO answers VALUES(5, 1, 'Orange');

INSERT INTO answers VALUES(6, 2, 'Parmesan');
INSERT INTO answers VALUES(7, 2, 'Mozarella');
INSERT INTO answers VALUES(8, 2, 'Swiss Cheese');
INSERT INTO answers VALUES(8, 2, 'Colby-Jac');
INSERT INTO answers VALUES(9, 2, 'Monterey Jack');


INSERT INTO answer_votes VALUES(1, 1, 1, 100, 1);
INSERT INTO answer_votes VALUES(2, 1, 2, 101, 1);
INSERT INTO answer_votes VALUES(3, 1, 3, 102, 1);
INSERT INTO answer_votes VALUES(4, 1, 4, 103, 1);
INSERT INTO answer_votes VALUES(5, 1, 5, 104, 1);
INSERT INTO answer_votes VALUES(6, 1, 5, 105, 1);
INSERT INTO answer_votes VALUES(7, 1, 5, 106, 1);
INSERT INTO answer_votes VALUES(8, 1, 3, 107, 1);
INSERT INTO answer_votes VALUES(9, 1, 3, 108, 1);
INSERT INTO answer_votes VALUES(10, 1, 2, 109, 1);
INSERT INTO answer_votes VALUES(11, 1, 2, 110, 1);
INSERT INTO answer_votes VALUES(12, 1, 2, 111, 1);
INSERT INTO answer_votes VALUES(13, 1, 5, 112, 1);
INSERT INTO answer_votes VALUES(14, 1, 5, 113, 1);
INSERT INTO answer_votes VALUES(15, 1, 5, 114, 1);
INSERT INTO answer_votes VALUES(16, 1, 1, 115, 1);

INSERT INTO answer_votes VALUES(17, 2, 6, 100, 1);
INSERT INTO answer_votes VALUES(18, 2, 7, 101, 1);
INSERT INTO answer_votes VALUES(19, 2, 7, 102, 1);
INSERT INTO answer_votes VALUES(20, 2, 7, 103, 1);
INSERT INTO answer_votes VALUES(21, 2, 7, 104, 1);
INSERT INTO answer_votes VALUES(22, 2, 6, 105, 1);
INSERT INTO answer_votes VALUES(23, 2, 6, 106, 1);
INSERT INTO answer_votes VALUES(24, 2, 8, 107, 1);

INSERT INTO answer_votes VALUES(25, 2, 8, 108, 1);
INSERT INTO answer_votes VALUES(26, 2, 9, 109, 1);
INSERT INTO answer_votes VALUES(27, 2, 9, 110, 1);
INSERT INTO answer_votes VALUES(28, 2, 7, 111, 1);
INSERT INTO answer_votes VALUES(29, 2, 7, 112, 1);
INSERT INTO answer_votes VALUES(30, 2, 6, 113, 1);
INSERT INTO answer_votes VALUES(31, 2, 7, 114, 1);
INSERT INTO answer_votes VALUES(32, 2, 8, 115, 1);

您可以使用以下查询：

SELECT      posts.id,
            posts.title,
            posts.content as Question,
            ans.content as Answer,
            COUNT(votes.answer_id) as TotalVotes
FROM        answers ans
INNER JOIN  posts posts on ans.post_id = posts.id
INNER JOIN  answer_votes votes on ans.id = votes.answer_id
WHERE       votes.vote = 1
GROUP BY    votes.answer_id,
            posts.id,
            posts.title,
            posts.content,
            ans.content
ORDER BY    posts.id,
            COUNT(votes.answer_id) DESC

您将看到以下结果集：

id      title                       Question                        Answer          TotalVotes
1     Favorite Color        Which is your favorite color?           Orange              6
1     Favorite Color        Which is your favorite color?           Red                 4
1     Favorite Color        Which is your favorite color?           Yellow              3
1     Favorite Color        Which is your favorite color?           Black               2
1     Favorite Color        Which is your favorite color?           Green               1
2     Favorite Cheese       Which is your favorite cheese?          Mozarella           7
2     Favorite Cheese       Which is your favorite cheese?          Parmesan            4
2     Favorite Cheese       Which is your favorite cheese?          Colby-Jac           3
2     Favorite Cheese       Which is your favorite cheese?          Swiss Cheese        3
2     Favorite Cheese       Which is your favorite cheese?          Monterey Jack       2

你可以在这里看到->

注：这不包括尚未投票的答案

编辑：我知道您希望包含尚未投票的答案。您可以通过如下方式稍微修改上述查询来实现这一点：

SELECT      posts.id,
            posts.title,
            posts.content as Question,
            ans.content as Answer,
            COUNT(votes.answer_id) as TotalVotes

FROM        answers ans
LEFT JOIN   answer_votes votes ON ans.id = votes.answer_id
LEFT JOIN   posts posts ON ans.post_id = posts.id
GROUP BY    posts.id,
            posts.title,
            posts.content,
            ans.content,
            votes.answer_id
ORDER BY    posts.id,
            COUNT(votes.answer_id) DESC

稍微修改上述数据集，如下所示：

INSERT INTO answer_votes VALUES(1, 1, 5, 100, 1)
INSERT INTO answer_votes VALUES(16, 1, 5, 115, 1)

请注意，现在没有人投票支持“黑色”的答案。此查询将生成以下结果集：

id      title                   Question                    Answer      TotalVotes
1   Favorite Color      Which is your favorite color?       Orange          8
1   Favorite Color      Which is your favorite color?       Red             4
1   Favorite Color      Which is your favorite color?       Yellow          3
1   Favorite Color      Which is your favorite color?       Green           1
1   Favorite Color      Which is your favorite color?       Black           0       /* Shows 0 votes for Black */
2   Favorite Cheese     Which is your favorite cheese?      Mozarella       7
2   Favorite Cheese     Which is your favorite cheese?      Parmesan        4
2   Favorite Cheese     Which is your favorite cheese?      Swiss Cheese    3
2   Favorite Cheese     Which is your favorite cheese?      Colby-Jac       3
2   Favorite Cheese     Which is your favorite cheese?      Monterey Jack   2

你可以在这里看到->

希望这有帮助

这里有很多答案都在SQL中。我将用PHP回答

这对拉威尔来说很有效

你需要有3个模型。运行

php artisan make:model

创建一个模型（我猜您已经知道了）

Post.php

，

Answer.php

，

vows.php

用雄辩来建立关系

在

Post.php

文件上，建立一个

one-to-many

关系，如下所示：

public function answers()
{
    return $this->hasMany('App\Answer', 'post_id', 'id');
}

在

Answer.php

文件上，创建另一个

one-to-many

关系，如下所示

public function votes()
{
    return $this->hasMany('App\Votes', 'answer_id', 'id');
}

现在，在同一文件上建立一个“属于”关系：

public function post()
{
    return $this->belongsTo('App\Post', 'post_id', 'id');
}

现在，您应该能够执行以下操作：

$answer = Answer::first();
$answer->post //This should get you the post the answer belongs to.

$answer->votes //Retuns all the votes an answer has. You can iterate through this array.

差不多就是这样。

这里有很多答案都在SQL中。我将用PHP回答

这对拉威尔来说很有效

你需要有3个模型。运行

php artisan make:model

创建一个模型（我猜您已经知道了）

Post.php

，

Answer.php

，

vows.php

用雄辩来建立关系

在

Post.php

文件上，建立一个

one-to-many

关系，如下所示：

public function answers()
{
    return $this->hasMany('App\Answer', 'post_id', 'id');
}

在

Answer.php

文件上，创建另一个

one-to-many

关系，如下所示

public function votes()
{
    return $this->hasMany('App\Votes', 'answer_id', 'id');
}

现在，在同一文件上建立一个“属于”关系：

public function post()
{
    return $this->belongsTo('App\Post', 'post_id', 'id');
}

现在，您应该能够执行以下操作：

$answer = Answer::first();
$answer->post //This should get you the post the answer belongs to.

$answer->votes //Retuns all the votes an answer has. You can iterate through this array.

差不多就是这样。

你想要它的PHP代码还是什么？@TaylorSwift是sql查询还是PHP代码。你想要它的PHP代码还是什么？@TaylorSwift是sql查询还是PHP代码。是的，我就是这么做的，但这个查询也不会得到尚未投票的答案，因为有三种投票的可能性：1票或0票，或者如果还没有人投票支持答案，就什么都没有。因此，此查询不获取第三种可能性，因为答案尚未添加到答案投票表中。是的，这就是我所做的，但此查询也不获取尚未投票的答案，因为有三种投票可能性：1或0，或者如果没有人投票支持答案，则不获取任何结果。因此，此查询不获取第三种可能性，因为答案尚未添加到答案投票表中。此检查的问题与此相同，您将了解问题所在我删除了答案id 1（黑色）的所有投票，但结果中未显示。您收到了吗？如果你不明白，告诉我。@HANZOSALAH我已经更新了我的答案！！请参见编辑的部分。这将为您提供没有投票的答案的结果。与此检查的问题相同，您将了解问题所在我删除了答案id 1（黑色）的所有投票，但它不会显示在结果中。您收到了吗？如果你不明白，告诉我。@HANZOSALAH我已经更新了我的答案！！请参见编辑的部分。这将为没有投票的答案提供结果。