What is virtual table?

We used to call a subquery a virtual table. (There are several definitions for the word 'virtual', but they sort of boil down to 'Not real. Something which is virtual has no physical basis itself but mimics a physical object in conceptual terms').

By the way, I also hear people call a subquery an 'inline view'.

i cannt understand virtual table.

A view is basically called a virtual table. View is nothing but a simple select query that joins more than one table and makes up to a sinlge one with the columns selected from different tables

Oracle virtual table means, hidden table which doesn't occupied any storage(memory) in the database. for eg: view in oracle

can u explain me the third normal form

read all that here

I am not sure but I think that virtual table is a table like dual table of ORACLE which is used to store temporal data.

You can write your own command by using the Add Command node in the Database Expert to create a virtual table which will represent the results of processing the command.