SQL | Derived tables and CTEs exercise | Show the number of events for the top 3 categories/countries

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.

Software ==> SQL  (198 exercises)
Version ==> Any version of SQL Server
Topic ==> Derived tables and CTEs  (13 exercises)
Level ==> Harder than average
Subject ==> SQL training
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). Once you've done this:
  1. Go into SQL Server Management Studio;
  2. Open the SQL file you've just unzipped (you can press CTRL + O to do this); then
  3. Execute this script.

This will generate the database that you'll need to use in order to do this exercise (note that the database and script are only to be used for exercises published on this website, and may not be reused or distributed in any form without the prior written permission of Wise Owl).

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Create two CTEs in the same query as follows:

CTE What it should list out
TopCountries The ids of the 3 countries with the most events (use TOP 3)
TopCategories The ids of the 3 categories with the most events (use TOP 3 again)

Use these to show all possible combinations in a final SELECT statement which should look like this:

-- combine these together (every possible combination)





TopCountries AS cy

CROSS JOIN TopCategories AS cg

The cross join gives all possible combinations of rows in the two CTEs - see below for what the results should look like.

You should now be looking at something like this:

Cross join results

There are 9 possible combinations.


If you still have the energy, use this to show the number of events for each combination:

Combination of events - full list

United Kingdom / Politics is the combination of country and category which has the most events.


Save this as Country category combinations, then close it down. 

You can unzip this file to see the answers to this exercise, although please remember this is for your personal use only.
This page has 1 thread Add post
06 Oct 17 at 10:51


I have completed the main task but i cannot  be able to append the NumberofEvents column - please help me with this.

06 Oct 17 at 11:58

We don't give out additional technical help, but maybe some kind reader would oblige?