SUM() as an Analytic Function

The SUM() function, when used as an analytic function, can provide running totals or cumulative sums across rows. This capability is essential for financial reporting and time-series analysis. For instance, to calculate a running total of sales amounts, you can write:

sqlCopy codeSELECT order_date, amount, SUM(amount) OVER (ORDER BY order_date) AS running_total FROM orders;

In this query, SUM(amount) calculates the cumulative sales amount as the date progresses. The result will show each order date along with the cumulative total of sales up to that date. This function is incredibly valuable for businesses looking to analyze trends over time, enabling them to see how sales accumulate and potentially correlate with other metrics.