Consider the following database schema:

$1.$ SUPPLIER$($SName$,$ ItemName, Price$)$ supplier SName sells item ItemName at Price.

$2.$ CUSTOMER$($CName$,$ Address$)$ customer CName lives at Address.

$3.$ ORDER$($CName$,$ SName, ItemName, Qty$)$ customer CName has ordered

Qty of item ItemName from supplier SName.

$4.$ ITEM$($ItemName$,$ Description$)$ Information about items.

Further, suppose that you want to add the following constraint to this diagram: Every item is supplied by some supplier. Draw the EER diagram from which the above schema might have been derived. Specify $($a$)$ keys, $($b$)$ structural constraints, and $($c$)$ roles $($if this is necessary$).$ For the constraints use both the traditional notation $($single$/$double lines and numbers across the diamonds$)$ and the $($min$,$ max$)$ notation. State clearly any additional assumptions that you made in designing the ER diagram.