Select datatable.model as price from (
Select P.model,P.price from PC P where P.price=(select Max(Q.price) from PC Q)
Union
Select P.model,P.price from Laptop P where P.price=(select Max(Q.price) from Laptop Q)
Union
Select P.model,P.price from Printer P where P.price=(select Max(Q.price) from Printer Q)
) as datatable where datatable.price=(
Select Max(newtable.price) as price from (
Select P.model,P.price from PC P where P.price=(select Max(Q.price) from PC Q)
Union
Select P.model,P.price from Laptop P where P.price=(select Max(Q.price) from Laptop Q)
Union
Select P.model,P.price from Printer P where P.price=(select Max(Q.price) from Printer Q)) as newtable)