> Selling price of the item is filled with accounts of fields Selling price of the product.
So the routine that computes that needs to be passed the ID of the product. What's the problem?
>b)The product must have at least one food composition.
A business rule to be implemented in the form that records sales?
>This is checked on line:
>AUR trigger when the products can "see" the old value in oznaka_potvrde = N,
>a new value = D calls a procedure that checks the rule.
Refers to items & processes you know about and we don't.
> c)Quantity field in the table output_groceries is calculated once a day.
>Remembers the total amount of input supplies for the day and MT.
>When processing a document heading confirmation_mark changing from N to Y.
Sounds like an incomplete statement of a business rule.
Presumably the schema you've outlined was developed from a procedure like that described in
http://www.artfulsoftware.com/dbdesignbasics.html. To answer the questions you've asked, we'd need much more of that requirement analysis, and that's not practical in a forum like this. The general principle that applies to your stage of development is that for each requirement item you're trying to implement that the current schema fails to support, you need to change the schema. The process is just dogged one-step-at-a-time analysis.