1. Learn
    2. /
  2. Courses
    3. /
  3. Improving Query Performance in SQL Server

Exercise

Remove duplicates with DISTINCT()

You want to know the closest city to earthquakes with a magnitude of 8 or higher. You can get this information from the Earthquakes table. However, a simple query returns duplicate rows because some cities have experienced more than one magnitude 8 or higher earthquake.

You can remove duplicates by using the DISTINCT() clause. Once you have your results, you would like to know how many times each city has experienced an earthquake of magnitude 8 or higher.

Note that IS NOT NULL is being used because many earthquakes do not occur near any populated area, thankfully.

Instructions 1/3

undefined XP
    1
    2
    3
  • Add the closest city and view the output of the query to confirm duplicated rows.