mysql - Foreign Key based on the sum of a related table -

I'm thinking that all this is possible.

I was watching Wikipedia through normal forms and came across. I have a similar set on the second set of tables in the referenced link, though, what if I did not want to make the "Net Worth Dollar" column, but instead there was another table in which all their sales were listed on the basis of their sales Is there any way to determine the position of money through the foreign key?

OK I think I have taken a better way of doing this. And it's using a trigger after triggering