# Exercise: Show substitute values for nulls in one of 3 different ways

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 course listed below!

 Category ==> SQL  (156 exercises) Topic ==> Calculations  (7 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). 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).

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.

The tblContinent table lists out the world's continents, but there are gaps:

You need to fill in the gaps!  Read on ...

Add up to 3 columns to show a message where a summary is missing:

This is what your query should show - see notes below.

Here's what your 3 columns should use:

Column How to get it
Using ISNULL Use the IsNull function to substitute the words No summary for rows where the Summary column is null.
Using COALESCE Do the same thing, but using the COALESCE function instead.
Using CASE Use a CASE WHEN statement to show different things according to whether the Summary column is null or not.

Take a moment to think which method you liked best, then save your query as Missing summaries and close it down.