Calculate running total / running balance

Question

I have a table:

create table Transactions(Tid int,amt int)

With 5 rows:

insert into Transactions values(1, 100)
insert into         


        

Answer 1

With the 2012 SUM and OVER functions you can now nest sum and counts.

SELECT date, sum(count(DISTINCT unique_id)) OVER (ORDER BY date) AS total_per_date
FROM dbo.table
GROUP BY date