Smartforms need to generate one DC NO

Hi Experts,

I am developed one Delivery challan smartform.

It's working is fine, but the probelm is i am create one ZTABLE with the fields (Date, Delivery Number,Route ,DCNO and CDCNO) while i am execute the smartforms i need to update the DCNO with some number like 1234 with check the condition Delivery no is not euql to space and DC no is space then i need to generate the DC NO .

How to proceed DC NO like 1234 , 1235 1236 like that.

Pls helpme.

Thanks in Advance

purnaneelu