MSSQL

SELECT a.CountryRegion, a.StateProvince, a.City,
CHOOSE (1 + GROUPING_ID(a.CountryRegion) + GROUPING_ID(a.StateProvince) + GROUPING_ID(a.City),
        a.City + ' Subtotal', a.StateProvince + ' Subtotal',
        a.CountryRegion + ' Subtotal', 'Total') AS Level,
SUM(soh.TotalDue) AS Revenue
FROM SalesLT.Address AS a
JOIN SalesLT.CustomerAddress AS ca
ON a.AddressID = ca.AddressID
JOIN SalesLT.Customer AS c
ON ca.CustomerID = c.CustomerID
JOIN SalesLT.SalesOrderHeader as soh
ON c.CustomerID = soh.CustomerID
GROUP BY ROLLUP(a.CountryRegion, a.StateProvince, a.City)
ORDER BY a.CountryRegion, a.StateProvince, a.City;


The CHOOSE method gives us back the text that matches the neumric value starting with 1, as 
CountryRegion	StateProvince	City	Level	Revenue
NULL           Null         NULL  Total 17898      -->  The total comes in level as the in CHOOSE mehod with GROUPING_ID we are getting 4 
UNIted Kingdom Null         NULL  United Kingdom Total 1876 -->  the name of region comes in level as we had the 3 in GROUPING_ID in CHOOSE method