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Software ==>	SQL (129 exercises)
Topic ==>	More exotic joins (2 exercises)
Level ==>	Average difficulty
Subject ==>	SQL training

Write an SQL outer join to show unmatched records in another table

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.

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

The database contains details of companions, and the episodes each appeared in:

Each companion can appear in one or more episodes.

Use this to list the names of the companions who haven't featured in any episodes. You should find there's one of them, but we won't spoil the surprise by saying who it is!

Create a query based on the companions table, with an outer join to the episode companion table.

Save this query as outre.sql (that's neither a misspelling nor a funny joke), and close it down.

You can unzip this file to see the answers to this exercise, although please remember this is for your personal use only.

You can find other training resources for the subject of this exercise here:

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From:	Aravindh_sql
When:	27 May 22 at 09:33

Reply to Aravindh_sql

SELECT
tblCompanion.CompanionName AS Companion,
tblEpisode.EpisodeType
FROM tblCompanion
LEFT JOIN
tblEpisodeCompanion
ON
tblCompanion.CompanionId = tblEpisodeCompanion.CompanionId
LEFT JOIN
tblEpisode
ON
tblEpisodeCompanion.EpisodeId = tblEpisode.EpisodeId
WHERE tblEpisode.EpisodeType IS NULL

ANSWER

-- Companion= Sarah Jane Smith

From:	FloridaMan
When:	26 Sep 21 at 01:28

Reply to FloridaMan

select *

from

[dbo].[tblEpisode] e

left join [dbo].[tblEpisodeCompanion] ec

on e.EpisodeId = ec.EpisodeId

--where e.EpisodeId is null

full outer join [dbo].[tblCompanion] c

on ec.CompanionId = c.CompanionId

From:	waltz
When:	09 May 21 at 11:23

Reply to waltz

SELECT cm.[CompanionId],[CompanionName]
FROM [dbo].[tblCompanion] AS cm left outer JOIN [dbo].[tblEpisodeCompanion] AS Ec
ON cm.CompanionId = Ec.CompanionId
except
(SELECT cm.[CompanionId],[CompanionName]
FROM [dbo].[tblCompanion] AS cm inner JOIN [dbo].[tblEpisodeCompanion] AS Ec
ON cm.CompanionId = Ec.CompanionId);
GO

From:	walteragwe
When:	20 Jan 21 at 03:43

Reply to walteragwe

From:	grao
When:	07 Nov 17 at 01:34

Reply to grao

I am not getting any results. Is this the right code?

use doctorwho

Select companionname
from tblCompanion as c
left outer join tblEpisodeCompanion as e
on c.CompanionId=e.EpisodeCompanionId
where e.EpisodeCompanionId =null

From:	DbEnthusiast
When:	19 Dec 20 at 16:11

Reply to DbEnthusiast

SELECT C.CompanionName,C.WhoPlayed,EC.*
FROM [dbo].[tblCompanion] C
LEFT JOIN [dbo].[tblEpisodeCompanion] EC ON C.CompanionId = EC.CompanionId
WHERE EC.EpisodeCompanionId IS NULL OR EC.CompanionId IS NULL

From:	Phithel
When:	18 Oct 18 at 18:57

Reply to Phithel

USE DoctorWho

SELECT
   C.[CompanionName],
   E.[Title]
FROM
   [dbo].[tblCompanion] AS C
       LEFT OUTER JOIN [dbo].[tblEpisodeCompanion] AS EC
           ON C.CompanionId = EC.CompanionId
       LEFT OUTER JOIN [dbo].[tblEpisode] AS E
           ON EC.EpisodeId = E.EpisodeId
WHERE
   E.Title IS NULL

I got Sarah Jane Smith

From:	linjom
When:	19 Apr 18 at 07:21

Reply to linjom

select c.CompanionName,c.WhoPlayed,E.Episodeid,E.EpisodeCompanionId
from tblCompanion as C
   left join tblEpisodeCompanion as E
   on c.CompanionId = E.CompanionId
   where (E.EpisodeCompanionId is null or E.EpisodeId is null)

Result i got Sarah Jane Smith Elisabeth Sladen NULL NULL

From:	Zerish
When:	16 May 18 at 07:33

Reply to Zerish

Right join will do just fine

SELECT [CompanionName]
FROM [dbo].[tblEpisodeCompanion]
RIGHT JOIN [dbo].[tblCompanion]
ON tblEpisodeCompanion.CompanionId=tblCompanion.CompanionId
WHERE EpisodeCompanionId IS NULL

From:	Sevid
When:	23 Mar 18 at 00:50

Reply to Sevid

You must use "where e.CompanionId is null", this is the result that I got :

CompanionName CompanionId WhoPlayed
Sarah Jane Smith 8 Elisabeth Sladen

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Write an SQL outer join to show unmatched records in another table

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