来自两个表的数据在连接时重复

Question

I have got two tables , I would use facebook POST as an example.

Post Table

Comment Table

My query

   $result = DB::table('posts')
            ->join('comments', 'posts.post_ID', '=', 'comments.post_ID')
            ->get();

I will receive an array of posts and comments merge. For each comments that exist , they will have the posts data.

What i want is to be able to do something like

foreach($posts as $post){
     foreach($post['comment']{

     }
}

Any idea how i can do that?

Answer 1

Something like this should work:

$result = DB::table('posts')
        ->join('comments', 'posts.id', '=', 'comments.post_id')
        ->get();

In the view:

@foreach($posts as $post)

    {{ $post->post_title }}
    {{ $post->message }}

@endforeach

Make sure that, field names in ->join('comments', 'posts.id', '=', 'comments.post_id') are right or change accordingly. post_title/comment_text is used to demonstrate the example, change to it's original table's field name and {{ }} is used in the example to echo the data, if you are not using Blade then use echo $post->post_title instead.

Update::

If you use Eloquent then use:

// Assumed you have defined comments as relationship method
$posts = Post::with('comments')->get(); // it's faster and called eager loading

Then in the view:

@foreach($posts as $post)

    {{ $post->post_title }}

    @foreach($post->comments as $comment)

        {{ $comment->message }}

    @endforeach

@endforeach

Answer 2

I will receive an array of posts and comments merge. For each comments that exist , they will have the posts data.

This is correct SQL behavoir when using a join. You will get the contents of both the rows inside the posts and comments rows on your JOIN .

According to Laravel 4.2's documentation on the join method , the parameters of the join function are:

join($table, $one, $operator = null, $two = null, $type = 'inner', $where = false)

Using an INNER JOIN , you are only going to get rows returned to you with your query (using an inner join) if you have a comment for all of the posts that you want data from. Additionally, with your INNER JOIN , if there is no comment on your post, you will not get any posts returned to you.

Also, you are not going to be able to separate all of your comments from your posts, which may mean that you are getting results returned for posts that you

The simple way to solve this for you would be to make two eloquent models:

class Post extends Eloquent {
    protected $table = 'posts';

    public function getComments() {
        return $this->hasMany('Comments', 'post_id');
    }
}

class Comments extends Eloquent {
    protected $table = 'comments';
}

From that you can query for all of the posts with eager loading :

$posts = Post::with('comments')->get();

and inside your view, you go:

foreach($posts as $post) {
    // echo the $post? (title, author etc)
    foreach($post->comments() as $comment) {
       // echo the $comment? (author, content etc)
    }
}