Question

I’m pretty new to codeigniter and I am trying to get to know databases better so I decided to follow this guide.

However I want to go a bit more advanced and try it over multiple pages with multiple tables, I have sort of got it half working but when I click add to cart it always selects the item from database 1. It uses

$this->db->where('id', $id);  
$query = $this->db->get('fruit', 1);  

to add the item to the cart. But I want it to be able to select from more than one table eg. fruit and veg where they would both be in a different table but have the same columns, is there anyway to easily do this using joins or any other method?

Answer 1

Yes, have you look into codeigniter active record?

Something like?
$this->db->select('*');
$this->db->from('fruit');
$this->db->join('veg', 'fruit.id = veg.id');

$query = $this->db->get();

// Produces:
// SELECT * FROM fruit
// JOIN veg ON veg.id = fruit.id

Edit:
From your description in your comment, I constructed these two tables.

   mysql> desc fruit;
   +-------+-------------+------+-----+---------+-------+
   | Field | Type        | Null | Key | Default | Extra |
   +-------+-------------+------+-----+---------+-------+
   | id    | int(11)     | NO   |     | NULL    |       |
   | name  | varchar(29) | NO   |     | NULL    |       |
   | price | int(11)     | YES  |     | NULL    |       |
   +-------+-------------+------+-----+---------+-------+
   3 rows in set (0.00 sec)

   mysql> desc veg;
   +-------+-------------+------+-----+---------+-------+
   | Field | Type        | Null | Key | Default | Extra |
   +-------+-------------+------+-----+---------+-------+
   | id    | int(11)     | NO   |     | NULL    |       |
   | name  | varchar(20) | NO   |     | NULL    |       |
   | price | int(11)     | YES  |     | NULL    |       |
   +-------+-------------+------+-----+---------+-------+
   3 rows in set (0.00 sec)

This is an example of the function test using multiple and joins. I think this is your final sql query?

SELECT *
FROM (`fruit`)
JOIN `veg` ON `fruit`.`id` = `veg`.`id` and fruit.name = veg.name and fruit.price = veg.price
WHERE `fruit`.`id` =  1

And this is the corresponding codeigniter query.

public function testJoins() {
    $id = 1;
    $this->db->select('*');
    $this->db->from('fruit');
    $this->db->join('veg', 'fruit.id = veg.id and fruit.name = veg.name and fruit.price = veg.price');
    $this->db->where('fruit.id', $id);

    $query = $this->db->get();
    return $query->result();
}