1. Which expression calculates a running total of order amounts sorted by date?
- SUM(total_amount) OVER (ORDER BY order_date)
- SUM(total_amount) GROUP BY order_date
- RUNNING_SUM(total_amount)
- SUM(total_amount) OVER (PARTITION BY order_date)
Hint: The default frame with ORDER BY runs from the start of the partition to the current row, calculating a running sum.