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SQL | Derived tables and CTEs exercise | CTEs to show continents with many events but few 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.
You can learn how to do this exercise if you attend one of more of the courses listed below!
- Go into SQL Server Management Studio;
- Open the SQL file you've just unzipped (you can press CTRL + O to do this); then
- 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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The aim of this exercise is to list out all the continents which have:
- At least 3 countries; but also
- At most 10 events.
It's worth noting that there are many ways to solve this in SQL, but as is so often the case CTEs seem to give the most intuitive approach.
To do this, all that you need to do is to create the following CTEs:
|CTE||What it should contain|
|ManyCountries||A list of continents having at least 3 countries|
|FewEvents||A list of continents in which no more than 10 events occurred|
You can then join them together to show that there is only one country in both camps. We won't spoil the surprise, but it has (in the Wise Owl database, at any rate) 4 countries and 9 events.
Optionally, save this as Toto.sql, then close it down.