This table shows the activities of workers and how many tasks they finished by the date. Each row is a record of a worker who logged in a computer and finished a number of tasks (it could be 0, no task was finished) on that date. Some sample records are listed below:

Write an SQL query that reports for each worker and date, how many tasks finished so far by the worker. That is, the total number of tasks finished by the worker until that date.

worker_id | computer_id | event_date | tasks + -+ 5 3 1 11 11 21 3 3 1 11 2 | 2019-03-01 2 | 2019-05-02 3 | 2020-06-25 1 | 2019-03-02 4 | 2020-07-03 3 | 2020-08-02 2 4 Expected result: worker_id | event_date | tasks_finished_so_far 5 8 1 | 2019-03-01 1 | 2019-05-02 1 | 2020-08-02 2 | 2020-06-25 3 | 2019-03-02 3 | 2020-07-03 12 1 2