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Exercises

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Software ==>	SQL (203 exercises)
Topic ==>	Temporary tables and table variables (13 exercises)
Level ==>	Average difficulty
Subject ==>	SQL training

Use a table variable to hold useful information from several sources together

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.

Before you can do this exercise, you'll need to download and unzip this file . Once you've done this:

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).

The aim of this exercise is to create a table variable, and populate it so that it holds the category, country and continent with the highest number of events for each:

Where we should end up - although there's a way to go yet to get there.

The easiest way to start is to first write three select statements:

Use apostrophes to create the first column value for each row (eg 'Category'); the other two columns come from combining SELECT TOP 1 with a GROUP BY clause.

Now declare a TABLE variable with three columns: Source, Winner and Number of events. Insert the results of your three SELECT statements into this table, either by using UNION or by using 3 separate INSERT statements.

You should now be able to display the results of this query: