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Software ==>	SSAS - tabular (30 exercises)
Topic ==>	Measures (3 exercises)
Level ==>	Harder than average
Subject ==>	SSAS training

Use AVERAGEX and CALCULATE to show true ratios of area to units for shopping centres

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).

If you haven't already done so, create a new project called BaseModel, and import the following tables: Centre, CentreType, Environment, Family, Habitat, Product, Purchase, Region and Town.

In the Centre table, create the following measures:

Name	What it shows
AverageMetres	The average square metres area for the filter context.
AverageUnits	The average number of units for the filter context.

This should allow you to create the following pivot table:

The average square metre area and number of units for each shopping centre type.

Create a measure called FalseAverage which divides the average metres by the average units, and show this in your pivot table:

The true average for any cell should be [the total square metres for that cell's filter context] divided by [the total number of units for that cell's filter context].

Now create a measure called TrueAverage which uses the AVERAGEX function to work out the true average ratio:

Notice that the figures are slightly different in each case.

The Shopping Centre row is returning an error because the Market Quay centre has 0 units (at least, according to our database), so we're getting a divide-by-zero error. To get round this, amend your true average to omit any centres where the number of units equals 0 to get: