Add a new column called running salary to the dataset, computing the cumulative sum of salaries.

To add a running salary column you can use a window function in SQL:

UPDATE employee_payments

SET running_salary = sub.running_salary

FROM (

SELECT

id,
SUM(salary) OVER (ORDER BY date ROWS UNBOUNDED PRECEDING) AS running_salary

FROM employee_payments

) AS sub

WHERE employee_payments.id = sub.id;

If you prefer to create a new table or view, simply select the columns plus the windowed sum as shown in the previous example. In pandas you would do:

df['running_salary'] = df['salary'].cumsum()

Both methods produce a column that accumulates the salary values in the order of the date column.