Sum values from multiple rows into one row

Question

In SQL Server 2012, I have a table my_table that has columns state, month, ID, and sales.

My goal is to merge different rows

Answer 1

Considering there should be an index on column id, this query would be a better solution:

select state, month, id, sum(sales) Total
from yourtable
group by id, state, month
order by id