how to change I/O field to radio button?

[kid94]

HI, experts

Now I'm learning ABAP in SAP and have one question that I cannot solve.

first, create I/O field with SDYN_CONN in screen painter

As we can see in the SPFLI transparent table, there are AA, AZ, DL and other datas in CARRID field which is same as SDYN_CONN-CARRID(Airline field in screen)

And I want to change this field to radio button with few datas from SPFLI.

I delete the I/O field in screen painter and create radio button from screen element.

but now I have to write flow logic for these radio buttons. I thought I need to create CASE statement and write SELECT statement for each button's function code to get proper data from SPFLI. Below code is what I thought.

I think this is little dirty and slow logic because for each button, program need to access DB to get data. I think this problem could be solved with internal tables but I really don't know how to write logic. 

Could you help me?