Hi

I would like to group rows based on order and similarity in a single
sql-query if possible:

A, 1, 50
A, 2, 50
A, 3, 100
A, 4, 50
A, 5, 100
A, 6, 100

Would come out as:

A, 1, 50, 2 <-- Last value shows number of grouped rows
A, 2, 100, 1
A, 3, 50, 1
A, 4, 100, 2

Any suggestions?