Difference between Alias Table vs Duplicate Table

Today my colleague asked me "what is difference between Alias Table and Duplicate Table?"

Here is the answer.....

Alias Table	Duplicate Table
Its a mirror image of the Parent Table	Its a Copy of the Parent Table
We can't edit or modify Alias Table	We can edit/modify/delete columns in Duplicate table
Changes made in Parent Table is automatically reflected in Alias table	Changes made in Parent table are not reflected in Duplicate table
Used : When there is a need to avoid self-join or circular join	Used when there is a need to use few columns of Parent table.

Its always good to use an Alias table, as it is more convenient in maintaining the RPD .


-Asifkhan P.