I think it's about time you finaly do some reading of oracle documentation, in particular The Concepts Manual.
Originally Posted by Vipassana
Untill you don't have at least a slightest idea what each of your two queries are doing and untill you don't know some of the very basic Oracle database vocabulary, any further explanation will only add more confusion. But nevertheless, I'll try to address some of your questions:
I'll leave this for your homework - I hope you'll managed to find out which of your two queries is doing what.
First of all which is which? I presume the first statement means "how much space is needed to store all those rows" and the second means "the other is how much space is actually allocated by that table".
It means all the rows that are currently in your PRODUCT table. It means NUM_ROWS from your first query.
What does "all the rows" mean here?
It means how much space do you need in the table to store those NUM_ROWS rows in it. Your query reported that you need approximately 14 Kb free space to store those rows in your table. So, if your create a new table to be 14Kb in size that would probably be sufficient to insert those rows in it. If you create your new table to be 64Kb, you'll be fine too - when you insert those rows that you currently have in your PRODUCT table, they will occupy about 14KB of your new table, leaving 50Kb free space in it. But if you create your new table to be 10Kb large, without the ability for it to dinamicaly add new extents, you won't be able to insert all of the rows from your PRODUCT table in it, because they require 14Kb (according to your formula), but you only have 10Kb free space in it.
And also what does "how much space is needed..." mean?
As I said, take a look at the Concepts manual and read about "blocks" and "segments" and "extents", about "data files" and "tablespaces". It will all become so clear......
Thridly I didn't understand what you meant by "the other is how much space is actually allocated by that table". You mean how is actually used? If so "used out of what (how much)?"