Exercise: String and Conditional Aggregation
Last Updated: May 12, 2026
1 min read
For this exercise, we will work with below data:
SQL
Exercise 1
Easy
Write a query that returns a single comma-separated list of distinct artist countries from the artists table, ordered alphabetically. Exclude NULL countries.
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Expected Query
Expected Output
Exercise 2
Easy
Write a query that returns the total amount of completed payments and the total amount of failed payments as two separate columns.
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Expected Query
Expected Output
Exercise 3
Medium
Write a query that returns each album's title, the count of tracks, and a comma-separated list of track titles ordered by track_number. Order results by album title.
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Expected Query
Expected Output
Exercise 4
Hard
Write a query that produces one row per album showing the album title, artist name, track count, total duration in seconds, and a comma-separated track listing ordered by track_number. Order results by album title.
SQL