I am trying to write a query that calculates the total revenue of products purchased in April. However, if the same product is purchased more than once in April, it is not included in the total amount. For example, if Ahmet bought an iPhone for 3000 lira each in April, and Mehmet also bought one, the total should show 6000 lira instead of 3000 lira. I believe the issue lies with the urun_id, but I have not come up with a solution. Your help is appreciated. Best regards.