Dear Experts

Table1 has following Five Fields

--Date---Opening---Receipt---Payment---Balance
02/06/08------0--------500----------100---------400
03/06/08------0--------200----------300---------300
04/06/08------0--------800----------200---------900


How to fillout Opening columns as

--Date---Opening---Receipt---Payment---Balance
02/06/08------0----------500---------100---------400
03/06/08----400--------200----------300---------300
04/06/08----300--------800---------200---------900


Please help