The Projection Operation
Consider the query:
select distinct name,age from Employee;
|
If the Employee relation has four tuples such as:
(94002, John, Sales, Manager, 32)
(95212, Jane, Admin, Manager, 39)
(96341, John, Admin, Secretary, 32)
(91234, Jane, Admin, Secretary, 21)
|
then the result of the projection is:
(Jane, 21) (Jane, 39) (John, 32)
|
Note that duplicate tuples (e.g. (John,32) ) are eliminated.
|