在视图 oracle 中进行累积总和

I want to make a view in oracle, how can I get value of 'saldo' that I supposed like in this screenshoot with oracle? can someone give me the script?

我想要的结果:

dateacct   period_id   startdate   enddate     debit   credit   saldo
7/10/2015     1        1/10/2015   30/10/2015   25       0        25
8/10/2015     1        1/10/2015   30/10/2015   0        5        20
9/10/2015     1        1/10/2015   30/10/2015   0        3        17
10/10/2015    1        1/10/2015   30/10/2015   4        0        21

注意:dateacct、period_id、startdate、enddate、credit、debit 是我从 'akun' 表中取出的列.

SELECT DATEACCT, PERIOD_ID, STARTDATE, ENDDATE, CREDIT, DEBIT,
    SUM (DEBIT-CREDIT) OVER (ORDER BY DATEACCT,PERIOD_ID,STARTDATE,ENDDATE) saldo
from AKUN
ORDER BY DATEACCT, PERIOD_ID, STARTDATE, ENDDATE;