How i can generate count variable depending on another by id

[Rehman Najeeb]

Hi stata community,
I am struggling to solve problem stated above e.g
Please suggest stata code to generate sum_var2 based of id and var2

ID	var1	var2	sum_var2	var4
1	1	1	1
1	2	1	2
1	3	0	2
1	4	1	3
2	1	1	1
2	2	1	2
2	3	1	3
2	4	0	3
2	5	1	4
3	1	1	1
3	2	1	2
3	3	1	3
3	4	1	4
3	5	1	5
3	6	1	6
4	1	0	0
4	2	1	1
4	3	1	2
4	4	1	3
4	5	0	3
5	1	1	1
5	2	1	2
5	3	1	3
6	1	1	1
6	2	0	1

thanks,
Najeeb

[Joseph Coveney]

Try

bysort ID (var1): generate int sum_var2 = sum(var2)

[Rehman Najeeb]

Thank you so much Joshep Coveney