SQL | Calculations exercise | Show substitute values for nulls in one of 3 different ways

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Software ==> SQL  (198 exercises)
Version ==> Any version of SQL Server
Topic ==> Calculations  (7 exercises)
Level ==> Average difficulty
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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The tblContinent table lists out the world's continents, but there are gaps:

Continents list

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


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

Summaries filled in

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.

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 3 threads Add post
05 Feb 22 at 10:53

My Solution:

Alter Table tblContinent
Add [Using ISNUll] nvarchar(50) NULL

Alter Table tblContinent
Add [Using COALESCE] nvarchar(50) NULL

Alter Table tblContinent
Add [Using CASE] nvarchar(50) NULL

Update dbo.tblContinent
Set [Using ISNULL] = ISNULL(Summary, 'No Summary')

Update dbo.tblContinent
Set [Using COALESCE] = COALESCE(Summary, 'No Summary')

Update dbo.tblContinent
Set    [Using CASE] = CASE WHEN Summary is NOT NULL Then Summary Else 'No Summary' END

18 Jul 18 at 21:55

Continentid, continentName, Summary, 
ISNULL(Summary,'No Summary') as 'Using IsNull',
Coalesce(Summary,'No Summary') as 'Using COALESCE',
when summary is null then 'No Summary'
else summary
as 'Using Case'
from tblContinent

04 Jun 17 at 17:33

The WorldEvents database table dbo.tblContinent that I downloaded doesn't have a third column. Is that the case for others?

05 Jun 17 at 09:40

You're right!  I've updated the download file, and it should now be fine.  Thanks.