Need ABAP code for the below scenario...!

Hi Guru's

Please somebody can help me writing ABAP code for the below scenario..

I have a table in BW RSRD_SETT_NODE_A (Settid, objver,ID, index, value), here Value field is of String type.

my requirement is to replace the string value where '20141103' with 20141104' for filter value high and for filter value low.

Selection conditions are:  Settid = Testid,   Objver = 'A', and ID = 'PR_filetr_srig' .

Ex: Value filed for index 4 stored as below in the table row.

FILTER_OPERATOR_1=BT&FILTER_SIGN_1=I&FILTER_VALUE_HIGH_1=20141231&FILTER_VALUE_LOW_1=20141201

Please let me know for any more info.

Thanks in advance for your help.

Thanks