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SQL · PRACTICAL GUIDE

SQL Running Total

Calculate cumulative values in a defined order.

Practice SQLLearning path

What this solves

Track cumulative production quantity through a shift. This pattern is useful when the business question is clear but a generic tutorial is too abstract.

The rule

Use SUM as a window function with an ORDER BY.

SELECT EventTime, Qty, SUM(Qty) OVER(ORDER BY EventTime) AS RunningQty
FROM Production;

Real-work checklist

  1. Define the business key and expected grain before writing the formula, query or markup.
  2. Test the pattern on a small known sample where you can verify the answer manually.
  3. Check missing values, duplicates and data types before trusting a large result.
  4. Scale to the real file or database only after the logic is proven.

Common mistake

Running totals require a deterministic order; include a tie-breaker when timestamps can repeat.

Try it next

PracticeChange the example and verify the result.Use a toolMove from a small example to real work.Related contentFind guides, errors and scenarios on this topic.