Exercise: Use variables to show details for a given episode number

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 Wise Owl course listed below!

Category ==> SQL  (115 exercises)
Topic ==> Variables  (8 exercises)
Level ==> Relatively easy
Course ==> Advanced SQL
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First (if you haven't already done so) run the script shown above to generate the Doctor Who training database.

Start a query, creating a variable to hold the id number of the Doctor Who episode whose details you want to show:

USE DoctorWho

-- the episode number of interest

DECLARE @EpisodeId int = 54

The aim of this exercise is to get to the point where you can run this command:

-- list out the details for this episode


@EpisodeName as Title,

@EpisodeId as 'Episode id',

@NumberCompanions as 'Number of companions',

@NumberEnemies as 'Number of enemies'

Here's what this should show for episode id 54, for example:

Episode details

This episode featured 2 companions and 2 enemies.

First, create a variable called @EpisodeName and set this to hold the title of the episode with id number equal to the value of variable @EpisodeId.  The syntax that you'll need is:

DECLARE @VariableName VariableType = (

-- some select statement which returns a single value



Now create two variables and set their values as follows:

Variable name Value
@NumberCompanions The number of companions for this episode (ie the count of the number of rows in table tblEpisodeCompanion where the episode id equals the one contained in the variable @EpisodeId).
@NumberEnemies The number of enemies for this episode (this time counting the number of rows for this episode in table tblEpisodeEnemy).

Complete and run your query to check that it gives this output if you change the episode id to 42:

For the voyage of the damned

This episode had 1 companion and 2 enemies.

Optionally, save your query as Counting by numbers, then close it down.

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