Filtering out nulls

One way to deal with nulls is to simply filter them out. There are two important conditionals related to nulls:

IS NULL is true for any value that is null.
IS NOT NULL is true for any value that is not null. Note that a zero or a blank cell is not the same as a null.

These conditionals can be leveraged by several clauses, such as CASE statements, WHERE statements, and HAVING statements. In this exercise, you will learn how to filter out nulls using two separate techniques.

Feel free to reference the E:R Diagram.

This exercise is part of the course

Reporting in SQL

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Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

-- Show total gold_medals by country
SELECT 
	____,
    ____ AS gold_medals
FROM ____ AS w
JOIN ____ AS c
ON ____
GROUP BY ____
-- Order by gold_medals in descending order
ORDER BY ____;

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