How to count items for a specific ordernation

Hi everyone,

This is my table:

PACKAGE_ID | ITEM_ID 1 1 1 2 1 3 2 4 2 5 3 6 4 7 4 8

I want a new column called count that count 1 to N according to package ID. E.g.: PACKAGE_ID | ITEM_ID | COUNT 1 1 1 1 2 2 1 3 3 2 4 1 new package 2 5 2 3 6 1 4 7 1 4 8 2

Thanks!