Question

I have written a query which returns all records with some many-to-many joins correctly for the entire set or an individual article using WHERE a.id = ?

SELECT a.id, date_added, title, content, category_id, person_id, organization_id, c.name AS category_name, firstname, lastname, o.name AS organization_name

FROM articles AS a

LEFT OUTER JOIN articles_categories AS ac ON a.id=ac.article_id
LEFT OUTER JOIN categories AS c ON c.id=ac.category_id

LEFT OUTER JOIN articles_people AS ap ON a.id=ap.article_id
LEFT OUTER JOIN people AS p ON p.id=ap.person_id

LEFT OUTER JOIN articles_organizations AS ao ON a.id=ao.article_id
LEFT OUTER JOIN organizations AS o ON o.id=ao.organization_id

ORDER BY date_added

BUT!

I’ve hit a brick wall trying to work out how to limit the articles to a specific number of IDs, for working with pagination.

I’m ideally trying to use as simple and clear SQL statements as possible because I’m using the codeigniter framework with their active record class.
http://codeigniter.com/user_guide/database/active_record.html

Would really appreciate some help as I don’t want to revert to using multiple queries for this as I’ve tried to reduce it down to a single query for database efficiency.

Have search around and tried some alternatives but nothing seems to work. Many thanks!

For example the results I return are like this

---------------------------------------------------------------------
id     title        category_id       person_id       organization_id
---------------------------------------------------------------------
1      test              1                1                  1
1      test              2                1                  1
1      test              1                2                  1
1      test              1                1                  2
1      test              5                1                  1
1      test              8                1                  1
1      test              1                4                  1
1      test              1                4                  2
1      test              1                1                  1
2      test 2            2                1                  1
2      test 2            1                2                  1
2      test 2            1                1                  2
2      test 2            5                1                  1
2      test 2            8                1                  1
2      test 2            1                4                  1
2      test 2            1                4                  2

I need the results like this so that I can create sub-arrays in the php like this:

$articles = $query->result_array();

$output = array();

foreach ($articles as $article) {

    // set up article details   
    $article_id = $article['id'];

    // add article details
    $output[$article_id]['article_id'] = $article_id;
    $output[$article_id]['date_added'] = $article['date_added'];
    $output[$article_id]['title'] = $article['title'];
    $output[$article_id]['content'] = $article['content'];

    // set up people details and add people array with details if exists
    if (isset($article['person_id'])) {
        $person_id = $article['person_id'];

        $output[$article_id]['people'][$person_id]['person_id'] = $person_id;
        $output[$article_id]['people'][$person_id]['lastname'] = $article['lastname'];
        $output[$article_id]['people'][$person_id]['firstname'] = $article['firstname'];
    }

    // set up organizations details and add organizations array with details if exists
    if (isset($article['organization_id'])) {
        $organization_id = $article['organization_id'];

        $output[$article_id]['organizations'][$organization_id]['organization_id'] = $organization_id;
        $output[$article_id]['organizations'][$organization_id]['organization_name'] = $article['organization_name'];               
    }

    // set up categories details and add categories array with details if exists
    if (isset($article['category_id'])) {
        $category_id = $article['category_id'];

        $output[$article_id]['categories'][$category_id]['category_id'] = $category_id;
        $output[$article_id]['categories'][$category_id]['category_name'] = $article['category_name'];
    }       

}

But if I just use LIMIT (with offset etc) 1

the results I get are

---------------------------------------------------------------------
id     title        category_id       person_id       organization_id
---------------------------------------------------------------------
1      test              1                1                  1

instead of

---------------------------------------------------------------------
id     title        category_id       person_id       organization_id
---------------------------------------------------------------------
1      test              1                1                  1
1      test              2                1                  1
1      test              1                2                  1
1      test              1                1                  2
1      test              5                1                  1
1      test              8                1                  1
1      test              1                4                  1
1      test              1                4                  2
1      test              1                1                  1

which is my desired result.

Answer 1

OK, so finally I worked out how it is possible.

Thought i’d include it here in case anyone else has the same problem.

Changing this line

FROM articles AS a

to this

FROM (SELECT * FROM articles LIMIT 5,3) AS a

does what I wanted.