CodeIgniter/PHP/MySQL: Retrieving data with JOIN

Question

I\'m new to PHP/MySQL and super-new to CodeIgniter.. I have information in many MySQL tables. I want to retrieve it with JOIN where the tables primary keys are equal to $var

Answer 1

Jon is right. Here's an example:

$this->db->select('movies.id, 
                   movies.title, 
                   movies.year, 
                   movies.runtime as totaltime,  
                   posters.poster_url');
$this->db->from('movies');
$this->db->join('posters', 'movies.id= posters.id');
$this->db->where('movies.id', $id);
$q = $this->db->get();

This will return objects that have ->id, ->title, ->year, ->totaltime, and ->poster_url properties. You won't need the additional code to fetch the data from each row.

Don't forget, if the Active Record syntax gets a little unwieldy, you can use full SQL queries and get the same results:

$sql = "SELECT movies.id,
        movies.title,
        movies.year,
        movies.runtime as totaltime,
        posters.poster_url
        FROM movies
        INNER JOIN posters ON movies.id = posters.id
        WHERE movies.id = ?"

return $this->db->query($sql, array($id))->result();

Both forms will ensure that your data is escaped properly.

CodeIgniter Active Record

Query Binding in CodeIgniter

Answer 2

An asterisk will return all the fields. To return a subset of these, i.e. all fields apart form the repeated id field, simply list the columns which you require rather than use '*'.

It is often a good idea to not use asterisk anyway. In the future of the app, someone may add a large field to the table which will be surplus to your requirements, and will slow your queries.

Answer 3

Simply put with method chaining:

$this->db->select('*')
         ->from('movies')
         ->join('posters', 'movies.id= posters.id')
         ->where('movies.id', $id)
         ->get();

Answer 4

$this->db->select('*');
$this->db->from('blogs');
$this->db->join('comments', 'comments.id = blogs.id');
$query = $this->db->get();