Running totals

SQL Running Total Interview Questions

A running total carries a number forward as the rows advance: cumulative revenue, month-on-month change, a moving average. Growth and retention reporting is built almost entirely out of them.

What running total questions ask you to do

Across the questions here, these are the shapes that come up:

  • Build a cumulative total over time
  • Compare each period with the one before it
  • Work out a moving average over a fixed number of rows
  • Track a balance down an ordered ledger
  • Show progress as a share of the final total

Common mistakes with running totals

Leaving the frame unstated is the usual error. Given an order and nothing else, SQL treats every row sharing the same date as one step and gives them all the same total, so a whole day’s revenue appears against each of that day’s orders. Saying explicitly that the total runs from the beginning to the current row fixes it.

Questions to practice

Questions last reviewed 19 October 2026.

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