I’m getting some data table, of which customer id, day of month and use time.

I want to get from this table a pie of total use time by customer

I only succeed in getting a pie with the first use time by each customer.

Where did I go wrong?

Redash can only visualize the data you provide it with. It doesn’t manipulate your data.

If you want a pie chart with the total time, then you should have your query return this and not a breakdown by day.