SELECT region, country, SUM(sales) FROM orders GROUP BY ROLLUP(region, country) ORDER BY region, country;

SELECT region, country, SUM(sales) FROM orders GROUP BY ROLLUP(region, country) ORDER BY region NULLS LAST, country NULLS LAST;

Without NULLS LAST, subtotal rows (with NULL) appear before detail rows. Use NULLS LAST for logical ordering.

Always use NULLS LAST in ORDER BY with ROLLUP/CUBE

Medium

NULL subtotal rows appear first without NULLS LAST

SELECT region, SUM(sales) FROM orders GROUP BY CUBE(region, country);

SELECT region, country, SUM(sales) FROM orders GROUP BY CUBE(region, country);

All columns in ROLLUP/CUBE must appear in SELECT to see subtotal structure.

Include all ROLLUP/CUBE columns in SELECT

High

Missing country in SELECT but included in CUBE