selection based on date

i have to select data from covp table based on posting date instead of fiscal year as per my requirement . How do i give that in the where clause ?

select kokrs belnr buzei perio

wogbtr lednr objnr gjahr

wrttp versn kstar owaer budat

from covp into table i_covp

where kokrs = i_prps-pkokr and lednr = '00' and

objnr = i_prps-objnr and

gjahr ge yprevyear and

wrttp = '04' and versn = '000'

and kstar not in s_kstar.

I have to remove gjahr ge yprevyear and give posting date .

Say if the year is 2007 then i have to use dates from sep 1st 2006 to aug 31st 2007 and so on.

I appreciate your responses.