Exercise: Show the number of episodes written by each author

This exercise is provided to allow potential course delegates to choose the correct Wise Owl Microsoft training course, and may not be reproduced in whole or in part in any format without the prior written consent of Wise Owl.

The answer to the exercise will be included and explained if you attend the Wise Owl course listed below!

Category ==> SQL  (115 exercises)
Topic ==> Aggregation and grouping  (6 exercises)
Level ==> Relatively easy
Course ==> Introduction to SQL
Before you can do this exercise, you'll need to download and unzip this file (if you have any problems doing this, click here for help).

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If you haven't already done so, run the script in the above folder to generate the Doctor Who database.

The following diagram shows how the authors and episodes tables are related:

Authors and episodes

You're probably familiar with this by now!

Use this to show for each author:

  • the number of episodes they wrote;
  • their earliest episode date; and
  • their latest episode date.

If you sort these so that the most prolific authors come first, here are the first few of the 25 rows you should see:

Authors and episodes

Those who know their Doctor Who won't be surprised at the two leaders.


Save this query as Blink was the best, then close it down.

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