Update table in Oracle

hi,
i've an or_trans table wherein i have 3 columns rg_code, colltype, or_amount. my problem is if the value of my rg_code columns equals to 'M1' but his colltype equals to '04' the or_amount will not be save to that record but will go to it's repective record like M1 whos colltype equals to '01'.
how am i going to manipulate these data. i am thinking of dumping the records to a temporary table. but still i've a hardtime putting the right amount to it's place

regards,
danny