First of the column and last of the column

Question

hi there,
sorry if it is a repost, please redirect me if this topic has been discussed. thank you.
my question is how do i get the first entry of the particular column and the last entry of the same column without calculating the number of row?
as for now my way of doing it is
select column1 from table1 where rownum=1
and
select column1 from table1 where rownum=lastrow
but this takes up too much time....
appreciate for recommendations

Answer 1

"select column1 from table1 where rownum=lastrow"
I think this SQL statement will return nothing, the reason can be found here.
http://www.oracle.com/technology/oramag/oracle/06-sep/o56asktom.html
Get the last entry of the particular column:
select * from(
select column1 from table1 order by rowid desc
) where rownum = 1
Get the first entry of the particular column:
select * from(
select column1 from table1 order by rowid order by rowid
) where rownum = 1