Sql Allows a subquery expression to be used in the from cluse. If we use such an expression then we must give the result relation a name, and we can rename the attributes, We do this renaming by useing the as clause. For example, consider the subquery....
select Employee1, qty from
(
select Employeeid ,AVG( SampleQty) from Table
group by EmployeeID
) as
Result(Employee1, qty )
This subquery generates a relation consisting of the names of all employeeid and therir corresponding average sampleQty . The subquery result is named result, with rhe attributes Employee1, qty.
