Using Variables in BODS

Hi Experts,

i have a senario lets consider sample source table

pro_id     item_number     store_name

101          10                    store1

102          10                    store1

101          10                    store2

101          10                    store3

102          10                    store2

i need ouput as

pro_id     item_number     store_name

101          10                         store1, store2, store3

102          10                         store1, store2

plz help regarding this ....

Thanks & Regards,

Mahe