tally of conditions on a column
i have a col that could be one of 3 values for part type. each detail row of an order has apart# which may have one of these 3 values
so I want to tally for example
part type A Part type B part type c
2 3 1
this means that 2 rows had parts belonging to type A etc.
for each order then reset for next order.
How do code for this in formula?