MySQL Inner join and sum two columns

Question

I have the following tables

TABLE: appointments

ID | PRICE | PAID
48 |  100  | 180

TABLE: appointments_product

Answer 1

Use where to check if price is equal to paid and the use group by to group with appointment_id.

Answer 2

select a.ID,a.PRICE,a.PAID,a.id as AppId,
       sum(b.total) as ProdTotal 
from appointments a 
INNER JOIN appointments_products b ON a.id = b.appointment_id
group by a.ID,a.PRICE,a.PAID;

Answer 3

select b.Appointment_Id, a.price, a.PAID, a.id, sum(b.total) AS TotalProd FROM appointments_products AS b inner join appointments as a On Appointment_Id = a.Id group by Appointment_Id, a.Price , a.PAID , a.id HAVING a.PAID != (a.Price + sum(b.Total))