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  3. Introduction to SQL

Exercise

Making queries DISTINCT

You've learned that the DISTINCT keyword can be used to return unique values in a field. In this exercise, you'll use this understanding to find out more about the books table!

There are 350 books in the books table, representing all of the books that our local library has available for checkout. But how many different authors are represented in these 350 books? The answer is surely less than 350. For example, J.K. Rowling wrote all seven Harry Potter books, so if our library has all Harry Potter books, seven books will be written by J.K Rowling. There are likely many more repeat authors!

Instructions 1/2

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  • 1
    • Write SQL code that returns a result set with just one column listing the unique authors in the books table.
  • 2
    • Update the code to return the unique author and genre combinations in the books table.