Originally posted by jaggu
what I ment is, by using nested table will the query be faster than joinig multiple table.
No, under the covers nested tables are separate tables which get joined to the main table automatically via a hidden RAW(16) column.
IMHO, nested tables and varrays should NOT be used to create tables in the database. You can use Object Views to create a nested table view of ordinary tables if that helps your OO application to access the data. For all other purposes, e.g. ad hoc querying and reporting, simple relational tables are far superior.