Exercise: Use a CTE to show enemies in certain Dr Who episodes

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 ==> Derived tables and CTEs  (7 exercises)
Level ==> Average difficulty
Course ==> Advanced 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).

You need a minimum screen resolution of about 700 pixels width to see our exercises. This is because they contain diagrams and tables which would not be viewable easily on a mobile phone or small laptop. Please use a larger tablet, notebook or desktop computer, or change your screen resolution settings.

First (if you haven't already done so) run the script shown above to generate the Doctor Who training database.

The aim of this exercise is to show a list of all of the enemies appearing in Doctor Who episodes featuring Rose Tyler, but not David Tennant.

It's possible - probable, even - that you could do this with a single SELECT statement, but CTEs make it so much easier to divide a complicated query into two simpler parts!

First create a query to show the episode id numbers for the 13 episodes which feature Rose Tyler as a companion, but not David Tennant as the Doctor.

Linking to this as a CTE, show the 8 enemies which appear in these episodes (some more than once):

List of enemies

The enemies corresponding to episodes featuring Rose Tyler, but not David Tennant.


Optionally, save this query as Wonderful CTEs.sql, then close it down.

This page has 0 threads Add post