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.
Este exercício faz parte do curso
Improving Query Performance in SQL Server
Exercício interativo prático
Experimente este exercício completando este código de exemplo.
SELECT ___, -- Add the closest city
Country
FROM Earthquakes
WHERE Magnitude >= 8
AND NearestPop IS NOT NULL
ORDER BY NearestPop;