WISE OWL EXERCISES
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- More exotic joins (2)
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- Derived tables and CTEs (13)
- Dynamic SQL (4)
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SQL | More exotic joins exercise | Use outer joins to show companions who have no episodes
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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.
I am not getting any results. Is this the right code?
from tblCompanion as c
left outer join tblEpisodeCompanion as e
where e.EpisodeCompanionId =null
[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
E.Title IS NULL
I got Sarah Jane Smith
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