Codeigniter's Model with QueryBuilder JOIN query - mysql

Question

Really new to working with CI4's Model and struggling to adapt my existing MySQL JOIN queries to work with the examples in its User Guide.
I have adapted part of my code like so:
public function brand_name($brand_name_slug)
{
return $this->asArray()
->where('availability', 'in stock')
->where('sku !=', '')
->where('brand_name_slug', $brand_name_slug)
->groupBy('gtin')
->orderBy('brand_name, subbrand_name, product, size, unit')
->findAll();
}
It works fine. I have looked at examples, and figured out I can add the code ->table('shop a') and it still works, but I also need to to add the following JOIN statement:
JOIN (SELECT gtin, MIN(sale_price) AS sale_price FROM shop GROUP BY gtin) AS b ON a.gtin = b.gtin AND a.sale_price = b.sale_price
As soon as I add ->join('shop b', 'a.gtin = b.gtin and a.sale_price = b.sale_price') I get a '404 - File Not Found' error.
When I look at all examples of CI4 joins and adapt my code to fit, my foreach($shop as $row) loop generates a 'Whoops...' error because they end with a getResult() or getResultArray - instead of findAll().
Which is the way forward, and do I need to change my foreach loop.
Full MySQL statement:
SELECT * FROM shop a JOIN (SELECT gtin, MIN(sale_price) AS sale_price FROM shop GROUP BY gtin) AS b ON a.gtin = b.gtin AND a.sale_price = b.sale_price WHERE availability = 'in stock' AND sku != '' AND brand_name_slug = $brand_name_slug GROUP BY gtin ORDER BY brand_name, subbrand_name, product, size

Answer 1

Query builders have their limits. That's why the query method exists. If you have a complex query I'd advise you to just use $this->query();.
It will make you lose less time and effort converting something you know already works. And in the top of that, while converting complex queries you usually end up using the query builder but with big part of your SQL in it.
In your model extending CodeIgniter\Model :
$query = $this->db->query("SELECT * FROM shop a JOIN (SELECT gtin, MIN(sale_price) AS sale_price FROM shop GROUP BY gtin) AS b ON a.gtin = b.gtin AND a.sale_price = b.sale_price WHERE availability = 'in stock' AND sku != '' AND brand_name_slug = \$brand_name_slug GROUP BY gtin ORDER BY brand_name, subbrand_name, product, size");
// your array result
$result_array = $query->getResultArray();
// your object result
$result_object = $query->getResult();

Answer 2

BaseBuilder Class in Codeigniter expects the first join parameter to be the table name. So try passing the table name and join it on the table name itself. I haven't personally used the table aliases so I might also be wrong.
Following are the parameter that the JOIN query expects :
public function join(string $table, string $cond, string $type = '', bool $escape = null)
Here, it expects the first name be a table, so try out by switching aliases for the table's name directly.
For your second part of query, It would be better if you could show the whole error rather than just posting the first of the error.

Answer 3

Managed to figure it out in the end:
public function brand_name($brand_name_slug)
{
return $this
->db
->table('shop a')
->select()
->join('(SELECT sku, MIN(sale_price) AS sale_price FROM shop GROUP BY sku) AS b', 'a.sku = b.sku AND a.sale_price = b.sale_price')
->where('availability', 'in stock')
->where('a.sku !=', '')
->where('brand_name_slug', $brand_name_slug)
->groupBy('a.sku')
->orderBy('brand_name, subbrand_name, product, size, unit')
->get()
->getResult();
}
Thanks for all your pointers!