In SQL, discount rate for the whole period is ROUND(100.0 * SUM(discounts) / (SUM(revenue) + SUM(discounts)), 2) over the monthly table. On the sample data it returns 7.23.
Discount rate = Discounts ÷ (Revenue after discounts + Discounts) × 100
What you need
Discount rate is the share of gross sales you gave away as discounts: discounts divided by sales before discounts (net revenue plus discounts), times 100. You need these columns, here from the sample file monthly.csv:
- revenue: revenue (net of discounts)
- discounts: discounts given
CREATE TABLE monthly (
month TEXT, -- 'YYYY-MM'
revenue INTEGER,
discounts INTEGER
);Step by step
- Load monthly.csv into a table called monthly. The table only needs the month column and the columns below.
- Run the first query to get one row per month.
- Run the whole-period query. It adds up each column first and divides once; averaging the monthly results gives a different, usually wrong, answer.
The queries
SELECT
month,
ROUND(100.0 * discounts / NULLIF(revenue + discounts, 0), 2) AS discount_rate
FROM monthly
ORDER BY month;SELECT ROUND(100.0 * SUM(discounts) / NULLIF(SUM(revenue) + SUM(discounts), 0), 2) AS discount_rate
FROM monthly;What you should get
Run against the sample data, the code above returns these values (in percent):
| Month | revenue | discounts | discount_rate |
|---|---|---|---|
| 2026-01 | 4,12,000 | 31,000 | 7.00% |
| 2026-02 | 4,38,500 | 35,200 | 7.43% |
| 2026-03 | 4,71,200 | 29,800 | 5.95% |
| 2026-04 | 4,55,800 | 41,500 | 8.35% |
| 2026-05 | 5,02,300 | 38,800 | 7.17% |
| 2026-06 | 5,48,900 | 44,100 | 7.44% |
| Whole period | 28,28,700 | 2,20,400 | 7.23% |
₹2,20,400 ÷ (₹28,28,700 + ₹2,20,400) × 100 = 7.23%
Notes for SQL
- Integer columns divide as integers in PostgreSQL, SQLite and SQL Server, so 3 / 4 gives 0. Multiplying by 1.0 (or 100.0) first makes the division decimal.
- NULLIF(x, 0) turns a zero denominator into NULL, so the query returns NULL for that row instead of failing with a division-by-zero error.
- Tested on SQLite and DuckDB. SUM, NULLIF and ROUND work the same in PostgreSQL, MySQL and BigQuery; SQL Server uses TOP instead of LIMIT where a query has one.
Where discount rate misleads
- The denominator is sales before discounts. Dividing by revenue after discounts overstates the rate.
- Here "discount rate" means retail discounting. In finance the same words mean the rate used to discount future cash flows, which is unrelated.
- Bundled pricing ("3 for 2") is a discount even if no coupon was used. Count it the same way every period.
The full explanation, with a calculator, is on the Discount rate page.
Same metric, other tools
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- Python and SQL for data analysis, side by side — 3 min read
- How to find out what changed in your sales data — 2 min read
About the data on this page
The figures come from a small made-up dataset, printed above in full so you can check every number by hand. Download it as monthly.csv. The results are computed from those rows when the page is built, and the Excel formulas, SQL and Python on these pages are run against the same rows before publishing, so the code and the answers agree.
To get these numbers from your own data without writing formulas, try AnalyzeIt: ask in plain words and it shows the working behind every figure.
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