How to show the summation in each row of a measure with some conditions? [closed]

Let’s suppose that I have the following data:

CustomerID->Number->Date

1->2->1/1/2019,
1->3->2/1/2019,
2->1->1/1/2019,
2->6->2/1/2019

I want to have a column let’s call it Summation:

CustomerID->Number->Date->Summation

1->2->1/1/2019->2,
1->3->2/1/2019->5,
2->1->1/1/2019->1,
2->6->2/1/2019->7

I want that column Summation in each row to represent the total summation of customer from the first of the month until the day each row has.

How to do this in Python, SQL, or R?

Answer

In SQL Server

SELECT CustomerID,Number, DATE, SUM(Number) over (partition by CustomerID order by Date) as summation
from tab_name