more than one union or intersect operator

Hi,

        If there are many "union" and "intersect" in a SQL statement, how can I state the precedence of union and intersect. For example :

select id from database where keyword = 'computer' union
select id from database where keyword = 'science' intersect
select id from database where keyword = 'course'

The result of the above query will be difference if I execute the union and then intersect with the result of 3rd select. Received on Mon Feb 17 1997 - 00:00:00 CST