mysql query error

[tamil]

Hi,i have some query problems.

table name : USER

this is my table details:

lastname | firstname
--------------------
mani | raja
raja | guru
--------------------

Here guru's father ins raja. and raja's father is mani.so guru's grandfather is mani. now how can i get guru's grandfather name(mani) in query.
now i know only name(guru).

pl hlp

[chazzy]

select lastname from USER where firstname = (select lastname from USER where firstname='guru')

[tamil]

hi its working.very thanks to u.