Question

I have the models User, Post, Comment and Tag.

• User creates Post.
• Posts can have multiple Comment and Tag.

Each model has it’s own table, so there are tables ‘posts’, ‘comments’ and ‘tags’. Comments have a foreign key called ‘post_id’, while Tags have a many_to_many relation table called ‘post_tags’, in which there are two fields: ‘post_id’ and ‘tag_id’.

I want to get a nested array like below:

• Which MySQL queries should I run?
• I suppose I need to alter the result with PHP to get my nested array. How?

Thanks a lot for your help 🙂

    [0] => Array
    (
        [Post] => Array
            (
                [id] => 1
                [title] => First article
                [content] => aaa
                [created] => 2008-05-18 00:00:00
            )
        [Comment] => Array
            (
                [0] => Array
                    (
                        [id] => 1
                        [post_id] => 1
                        [author] => Daniel
                        [email] => [e-mail]
                        [website] => http://example.com
                        [comment] => First comment
                        [created] => 2008-05-18 00:00:00
                    )
                [1] => Array
                    (
                        [id] => 2
                        [post_id] => 1
                        [author] => Sam
                        [email] => [e-mail]
                        [website] => http://example.net
                        [comment] => Second comment
                        [created] => 2008-05-18 00:00:00
                    )
            )
        [Tag] => Array
            (
                [0] => Array
                    (
                        [id] => 1
                        [name] => Awesome
                    )
                [1] => Array
                    (
                        [id] => 2
                        [name] => Baking
                    )
            )
    )
    [1] => Array
    (
        [Post] => Array
            (...

Answer 1

You better of doing 3 queries.

1. first fetch post (, and left join the user if you need it), and store them like:

   $list[$row['post_id']]['Post'] = $row;
   

2. then fetch all post-comments and store them as

   $list[$row['post_id']]['Comment'][$row['comment_id']] = $row;
   

3. then fetch all post-tags

   $list[$row['post_id']]['Tags'][$row['tag_id']] = $row;
   

that far more effective than trying to use a single query,
as a single query going to end up sending the same data multiple times