SQL | Basic joins exercise | Link 3 tables together using inner joins and table aliases

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!

Software ==> SQL  (198 exercises)
Version ==> Any version of SQL Server
Topic ==> Basic joins  (8 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).

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.

If you haven't already done so, run the script in the above folder to generate the Doctor Who database.

Write a query using inner joins to show all of the authors who have written episodes featuring the Daleks.  You may find the following relationship diagram useful to refer to:

Three tables linked

How to get from enemies to authors in 3 easy jumps.

You should find that there are 16 such episodes!

When you've finished, save this as Enough joins for now, then close it down.

This page has 2 threads Add post
grao   Reply to graoReply
05 Nov 17 at 18:42

So is this the code?

use doctorwho

Select authorname

from tblauthor as a
inner join tblepisode as epi
on a.authorid = epi.authorid

inner join tblepisodeenemy as ene
on epi.episodeid = ene.episodeenemyid

inner join  tblenemy as enemy
on enemy.enemyid = ene.episodeenemyid

where title like '%Daleks%'

bhilarev   Reply to bhilarevReply
25 Oct 17 at 07:14

I just get only four rows ,

Select
x.AuthorName,y.EpisodeNumber,y.Title,y.EpisodeDate
From Author As x
INNER JOIN Episode As y
ON x.AuthorId = y.AuthorId
Where Title Like '%Daleks%';

Is this query correct?

linjom   Reply to linjomReply
19 Apr 18 at 06:32

Should have been ..

enemyname like' %Dalek%'

Andy B   Reply to Andy BReply
25 Oct 17 at 08:44

You're showing all the episodes whose titles contain the word Dalek, rather than all episodes which feature the Daleks.  So for example an episode entitled "Little tin men from space" might feature the Daleks, but wouldn't appear in your query. 

Add a new post