>Thanks for help. I used the following and it works:
>INDEX ON code1+code2 to code
>But another problem is that the "code2" is a character but not numeric.
>So it will show ---
>BBB $30 1 1
>CCC $20 1 11
>EEE $10 1 12
>FFF $20 1 2
>I have tried:
>INDEX ON code1+ val(code2) to code
>but it said it is a "misoperand error". I need to use character for the code2 in some purpose, so what can I do?

You could do the opposite and convert code1 to a string.

index on str(code1)+code2 to code