What is a Named Calculation? In what scenarios do you use it?

 A Named Calculation is a new column added to a Table in DSV and is based on an expression. This capability allows you to add an extra column into your DSV which is based on one or more columns from underlying data source Table(s)/View(s) combined using an expression without requiring the addition of a physical column in the underlying database Table(s)/View(s).

 
The expression used in the Named Calculation should conform to the underlying data source dialect. For example, if the underlying data source is SQL Server, then it should conform to T-SQL, If is it Oracle, then it should conform to PL/SQL, etc...

 
    Named Calculations can be used in many scenarios, following are some of the common scenarios:
      

 For creating Derived Columns. Say you have First Name and Last Name in the underlying data source Table/View and you want to get the Full Name as "First Name + space + Last Name". Such things can be added as a Named Calculation.

 
 For performing Lookup Operations. Say you have an Employee table which has AddressID and an Address table in which AddressID is the Primary Key. Now, to get the address information (say Country) into the Employee table in DSV, a Named Calculation can be added to the Employee table with the following expression:

(
  SELECT Country
  FROM Address
  WHERE AddressID = Employee.AddressID
)