Is it okay to live some tables not connected to anything?
I have a table with a set of discounts for deals. For each deal, discounts can be summed up, so I don't see the point in connecting the "deals" table and "discounts" table by discount id. I also can't just create INT field for a discount in the "deals" table because discount should be predefined in "discounts" table. How to better organize such database?
Here is the screenshot of the scheme of the DB I have came up with so far.
Same problem with services. Multiple services can be provided under one deal. Is there a type which can contain multiple strings or numbers?