postgresql - In PostGIS is it possible to create a View with a unique ID?

When I create a view in PostGIS is there any way to add a unique ID to that view? Just like the "gid" field in any other PostGIS table?

Edit: Sorry I should have included this in the original post. I am using PostGresql 9.0 and PostGIS 1.5.

Ando

Answer

You should be able to use the row_number() function as a column in your view. This works for Postgres 8.4 or higher.

http://www.postgresql.org/docs/current/static/functions-window.html

SELECT * FROM

( SELECT
    ROW_NUMBER() OVER (ORDER BY column_to_sort_by ASC) AS ROW_NUMBER,
    Col1, Col2
  FROM table_name
) myview_name

This should work in most databases including SQL Server, Oracle, and MySQL.