You are right --- I should ask the difference between truncate and delete

But now I have a new question regarding to the tablespace creation --- how should I define the growth rate of the tablespace when existing one is full? Should the 'NEXT' part always be equal of greater than the 'INITIAL' part OR the 'NEXT' part of tablespace is decided upon the biggest 'NEXT' part of a table? e.g. If I have a table that will grow 100M when the initial extent is full, then my tablespace should grow at least 100M when it gets full? What's the strategy behind?

Thanks!