does anyone know about Relational Algebra?

Hi

does anyone know about relational algebra in database.

for example how a query in SQL looks up a given info from tables

thanks

Relational algebra doesn't necessarily deal with how a db engine performs a select, for example.

In Oracle, the optimizer may one of two strategies: RULE based operations, COST based operations. How the engine actually creates the result set depends on a lot of pre-existing conditions. Ultimately all of the possible operations boil down to a group of several types of operations taken in varying order. EXPLAIN PLAN puts that information into the user's PLAN_TABLE.

Go to www.orafaq.org and do a search on optimizer and EXPLAIN PLAN to see what I men.