Hey Disha,
I think you are worried about how to generate(add) dynamic columns. I'm attaching a small piece of code that will serve your purpose. Download it and upload in your system. Trace and learn it.
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Another way is to have an ITAB with maximum possible columns. And adjust add them in the field_catlog as per your requirement(logic). Though it looks difficult in the beginning But not much hard once you get the grip of it.
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Regards,
N.G.
