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Exercise

GROUP BY

In an earlier exercise, you wrote a separate WHERE query to determine the amount of demand lost for a specific region. We wouldn't want to have to write individual queries for every region. Fortunately,you don't have to write individual queries for every region. With GROUP BY, you can obtain a sum of all the unique values for your chosen column, all at once.

You'll return to the grid table here and calculate the total lost demand for all regions.

Instructions

100 XP
  • Select nerc_region and the sum of demand_loss_mw for each region.
  • Exclude values where demand_loss_mw is NULL.
  • Group the results by nerc_region.
  • Arrange in descending order of demand_loss.