Instruction
Good job! Of course, you can use any other ranking function in the same way:
SELECT Id, Country, City, Rating, NTILE(2) OVER(PARTITION BY Country ORDER BY OpeningDay ASC) AS GroupNo FROM Store;
In the above query, the stores are divided into two groups: older and newer stores. These groups are created separately for each country.
Exercise
Take the sales between August 1 and August 10, 2016. For each row, show the StoreId, the Day, the Revenue on that day, and the quartile number based on the Revenue of that store in descending order. Name the column Quartile.
Note: A quartile is one of four equal groups that are divided based on a value. In this case, we divide the rows into four groups based on store revenue.
Stuck? Here's a hint!
Use NTILE(4) and PARTITION BY StoreId ORDER BY Revenue DESC.



