select with multiple join and conditions where column null codeigniter

Question

I'm looking to get items from database where the items has options and some not.

My model to get the data is: {This return only products that product.id is in options and option_values}

$category_id = 2;
$this->db->select('category_products.*, products.*, option_values.price as prodPrice, option_values.special_price, LEAST(IFNULL(NULLIF(option_values.special_price, 0), option_values.price), option_values.price) as sort_price', false)
         ->from('category_products')
         ->join('products', 'category_products.product_id=products.id')
         ->join('options', 'options.product_id=attributes.product_id')
         ->join('option_values', 'option_values.option_id=options.id')
         ->where('category_products.category_id', $category_id)
         ->where('option_values.inventory >', '0');
         ->where('products.quantity >', '0');
$this->db->group_by('products.id');

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

But i need to get also items that has no options and options_values.

category_products table:

product_id | category_id | sequence
74 | 2 | 0
75 | 2 | 0

products table:

id | code | name | type | price | saleprice | quantity
74 | 12345_ | Product with options | 1 | 0 | NULL | 1
75 | 12346_ | Product without options | 2 | 199 | NULL | 1

options table:

id | product_id | sequence | name | type | required
74 | 74 | 1 | Size | radiolist | 1

option_values table:

id | option_id | name | value | price | special_price | weight | inventory | sequence | limit
777 | 74 | 8K | 12345 | 199.00 | 159.00 | 1.00 | 0 | 17 | NUL

With the model i write above i can get only the product_id 74, and my question is how can i adapt the query to get the product_id 75 to?

Any help is appreciated.

Answer 1

Try changing your joins to include LEFT JOIN . I don't have a database set up so I can't test it but I would try the following:

NOTE : the addition of the left parameters in the join() functions.

$category_id = 2;
            $this->db->select('category_products.*, products.*, option_values.price as prodPrice, option_values.special_price, LEAST(IFNULL(NULLIF(option_values.special_price, 0), option_values.price), option_values.price) as sort_price', false)
                    ->from('category_products')
                    ->join('products', 'category_products.product_id=products.id', 'left')
                    ->join('options', 'options.product_id=attributes.product_id', 'left')
                    ->join('option_values', 'option_values.option_id=options.id', 'left')
                    ->where('category_products.category_id', $category_id)
                    ->where('option_values.inventory >', '0');
                    ->where('products.quantity >', '0');
            $this->db->group_by('products.id');

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

            return $result;

You might need to modify the joins to be LEFT or RIGHT joins to get the desired result. I may try to simulate it a little later when I get a minute.

This is a good article on understanding MySQL joins. I refer to it from time to time when I have to craft complex queries.