Quiz on SQL ROLLUP

What is the main purpose of ROLLUP in SQL?

Which clause must be used with ROLLUP?

What is the output of:

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

Which of the following is equivalent to:

GROUP BY ROLLUP (a, b)

In `ROLLUP(a, b)`, what does the result with `a` = some value and `b` = NULL represent?

What will `ROLLUP` return when used on a single column like:

GROUP BY ROLLUP(category)

What does `ROLLUP` do that normal `GROUP BY` doesn’t?

Which of the following queries will give region → product subtotals and grand total?

SELECT region, product, SUM(sales)
FROM orders
GROUP BY ???;

What is returned at the very last row of a `ROLLUP` query result?

Which function helps detect if a column was aggregated by `ROLLUP` (i.e., NULL due to grouping)?

What will be the output of `GROUPING(product)` if the value is NULL due to a subtotal?

Which of the following creates **more** grouping combinations than `ROLLUP`?

How do NULLs behave in a `ROLLUP` result set?

What happens if you use `ORDER BY` with `ROLLUP` results?

What is the correct order of evaluation in a `ROLLUP` query?