WISE OWL EXERCISES
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SQL | Variables exercise | Use a variable to accumulate an episode's enemy names
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First (if you haven't already done so) run the script shown above to generate the Doctor Who training database.
The aim of this exercise is to show a list of all of the Doctor's enemies for a given episode:
What you would see for episode 15.
To start this, create a variable in a new query to hold the episode number:
-- choose a specific episode
DECLARE @EpisodeId int = 15
Now create another variable to hold the accumulated list of episode names:
-- variable to hold the list of enemies
DECLARE @EnemyList varchar(100) = ''
Write a SELECT statement which accumulates the list of enemy names for the chosen episode in a variable. The basis of this will be a statement starting like this:
-- add in each enemy name
@EnemyList = @EnemyList + ...
When you've done this, complete your query to show your results:
-- show the results
@EpisodeId as 'Episode id',
@EnemyList AS 'Enemies'
Optionally, save this query as Know your enemies.sql, then close it down.