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

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Software ==> SQL  (198 exercises)
Version ==> Any version of SQL Server
Topic ==> Basic joins  (8 exercises)
Level ==> Average difficulty
Course ==> Introduction to SQL
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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 3 threads Add post
LACubico   Reply to LACubicoReply
25 Sep 18 at 15:35

Use inner joins to link four tables to show Dr Who enemies by author.

USE DoctorWho
select a.AuthorId,a.AuthorName,
b.Title,b.episodetype,
c.EnemyId, d.EnemyName
from tblAuthor as a
inner join tblEpisode as b on
a.AuthorId = b.AuthorId
inner join tblEpisodeEnemy as c on
c.EpisodeId = b.EpisodeId
inner join tblEnemy as d on
d.EnemyId = c.EnemyId
where d.EnemyName = 'Daleks'

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. 

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