Comparing Column values with a constant

Hello,

How do i compare the column values with a constant.I have a column named 'STATUS' that has values like 'A' 'S' 'D' etc. I want to proceed only if any of these values is 'D'.
I mean it should compare one by one all values & proceed if the value comes as 'D'

How do i implement this using macros?

Thanks,
VIkram