how to search and autofill datagrid using 1st column

dear all

i have a invoice table

now in that datagrid table i have 4 columns

itemcode itemdescription qty price

now what i need is

user come to itemcode and whenever he type itemcode, he should get a list of initial alphabetic itemnames like if i type A so itemcode must show all items codes related to A

and when i get my required itemcode, after pressing enter it should fill the related field (item description,qty,price)

please guide with codes

thanks