表的列总和使用左连接返回null（codeigniter）

Question

I have this query:

$get_similar = $this->db->select('product.ar_id, product.title, likes.id, SUM(likes.up) as vote');
$get_similar = $this->db->from('product');
$get_similar = $this->db->join('likes', 'likes.id = product.id', 'left');
$get_similar = $this->db->where("MATCH (product.title, product.introduction) AGAINST ('$search') group by product.id LIMIT 6", null, false);
$get_similar = $this->db->get();    

For each row I get vote = null ! It's supposed to return 0 for only the products that don't have votes! Can you tell me where I made a mistake, please?

Answer 1

I think your error is here:

$get_similar = $this->db->join('likes', 'likes.id = product.id', 'left');

you are joining likes.id with product.id, i think you want to join something like "likes.product_id" with "product.id"