Exercise: Show which doctor/author combos are the most popular

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 ==> Average difficulty
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 tables you'll need for this exercise are as follows:

Three tables needed

You'll need to link each episode to its author and its doctor.

Write a query to list out for each author and doctor the number of episodes made, but restrict your output to show only the author/doctor combinations for which more than 5 episodes have been written.  Here's what you should see:

Episode listing

Here we've sorted the rows so the most common combination appears first.

 

You'll need to use the HAVING clause.  Remember that sweaty feet will give horrible odours!

Save this as Favourite combos, then close it down.

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