Re: Navigation vs Relational operators

> In what way is "navigation" different from using relational operators ?

In the data access context, navigation usually refers to:

1. Record-at-a-time traversal through an ISAM database. You make calls to a database library to get the next or previous record (using sequential or indexed access).
2. In a network model database, you navigate through pre-defined sets by making calls to get the next or prior member of the set, or the owner. It's conceptually similar to a doubly-linked list.
3. Relational is non-navigational. You don't need to know how to navigate to the data that matches your search criteria.

If you tell a taxi driver "Take Hwy 163 north to Interstate 8. Turn west on Interstate 8 until you come to Interstate 5. Turn North on Interstate 5 until the split at Interstate 405. Take I-405 North until you get to the West Century Blvd. exit. Turn west and take West Century Blvd. to Los Angeles Airport". That's navigation.

On the other hand, if you say "Take me to Los Angeles Airport", that's SQL. You rely on the driver to know the best route. Received on Sun May 16 2004 - 22:53:24 CEST