Instruction
Well done! Let's say we also need to add the general average repair duration to our report. To that end, we can use an empty pair of parentheses:
SELECT DateReceived, CustomerId, RepairCenter, AVG(RepairDuration) AS AvgRepairDuration FROM WarrantyRepair GROUP BY GROUPING SETS ( (CustomerId, RepairCenter), DateReceived, () )
As you can see, we can omit the parentheses for single statments – like DateReceived in this case.
Exercise
Run the template query. As you can see, a row with a general average was added.



