SUM() tidak berfungsi di MySQL:SUM() dengan DISTINCT

Anda memasukkan DISTINCT DI sum( rating.rating) as total_rating, itulah mengapa hasilnya(12=17-5 ), karena hanya akan menyertakan 5 satu kali saat menghitung jumlah.

 select review.comments, review.user_id, count(distinct rating.id) as rating_count,
    sum( rating.rating) as total_rating from users 
    left join review on users.id = review.user_id and review.shop_id='1' 
    left join rating on users.id = rating.user_id and rating.shop_id='1' 
    where review.shop_id='1' or rating.shop_id='1' 
    group by users.id, review.user_id, rating.user_id, review.id

Ini SQLFiddle

Contoh Output : Semoga membantu