Summing
Summing and counting are key ways of aggregating data, regardless of whether you are using a database, manipulating a spreadsheet, or using a programming language such as Python or R. Let's see how to do it in T-SQL using the grid table from Chapter 1.
You'll start by obtaining overall sums, focusing specifically on the 'MRO' region.
Bu egzersiz
Introduction to SQL Server
kursunun bir parçasıdırEgzersiz talimatları
- Obtain a grand total of the
demand_loss_mwcolumn by using theSUMfunction, and alias the result asMRO_demand_loss. - Only retrieve rows
WHEREdemand_loss_mwis notNULLandnerc_regionis'MRO'.
Uygulamalı interaktif egzersiz
Bu örnek kodu tamamlayarak bu egzersizi bitirin.
-- Sum the demand_loss_mw column
SELECT
___(demand_loss_mw) AS ___
FROM
grid
WHERE
-- demand_loss_mw should not contain NULL values
___ ___ ___ ___
-- and nerc_region should be 'MRO';
___ ___ = '___';