Page 154 - SQL

Conditions can also be joined to restrict the expression further:

select People where StartYear > 2005 and DepartmentID = 2

will result in the following table:

PROJECT

The project operator will return distinct field values from a table.
project < table > over < field list >

For example, examine the following expression:
project People over StartYear

This can be written as:

This will result in a table comprising of the distinct values held within the StartYear field of the
People table.

Duplicate values are removed from the resulting table due to the closure property creating a
relational table: all records in a relational table are required to be distinct.

If the field list comprises more than a single field then the resulting table is a distinct version of
these fields.
project People over StartYear, DepartmentID will return:

One record is removed due to the duplication of 2006 StartYear and 1 DepartmentID.

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