SAP HANA Calculation view concatenating

Hi all,i need your help to understand how to solve the following problem :

I suppose that i have an order (AUFK-AUFNR) and some operations description for it :

AUFNR   VORNR   LTXA1

1              10            text ltxa1 10

1              20            text ltxa1 20

1              30            text ltxa1 30

The result should be aggregated  by AUFNR on a single row :

AUFNR   LTXA1

1              text ltxa1 10 , text ltxa1 20 , text ltxa1 30

This has to be done inside a calculation view,but i don't know how...could you have some advices for me,please?

Have i to use cursor or loop on result set?

Thanks in advance.

Ciao.

Dario.