Example to populating UDA value based on another UDA value

Hi Experts,

Please help in providing any suitable example of populating a UDA value based on another UDA value using OPH rules or any other method. Following is what I am trying to achieve:

UDA1 - LOV is based on a table TABLE 1.Column A

UDA2 - If rownum=10 is select on TABLE 1.Column A in UDA1, I want to populate TABLE 1.Column B value (from rownum-10) in UDA2.

Both UDA1 and UDA2 are part of same attribute group.

All suggestions are welcome.

Thanks