Hi there, had a quick question about finding the number of occurrences of specific column. Let me give a quick example.

Table t:
col_1 | col2 | col_3
A | B
A | C
A | C
A | D
A | D
A | D

I want to put the number of occurrences of col_2 in a col_2.
should output:

col_1 | col2 | col_3
A | B | 1
A | C | 2
A | C | 2
A | D | 3
A | D | 3
A | D | 3

Any ideas what I can do for this?
Thank you very much.