SQL | Aggregation and grouping exercise | Show the number of episodes written by each author

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.

You can learn how to do this exercise if you attend one of more of the courses listed below!

Software ==> SQL  (198 exercises)
Version ==> Any version of SQL Server
Topic ==> Aggregation and grouping  (8 exercises)
Level ==> Relatively easy
Classroom ==> Introduction to SQL  /  Fast-track SQL
Online ==> Introduction to SQL  /  Fast-track 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.

The following diagram shows how the authors and episodes tables are related:

Authors and episodes

You're probably familiar with this by now!

Use this to show for each author:

  • the number of episodes they wrote;
  • their earliest episode date; and
  • their latest episode date.

If you sort these so that the most prolific authors come first, here are the first few of the 25 rows you should see:

Authors and episodes

Those who know their Doctor Who won't be surprised at the two leaders.

 

Save this query as Blink was the best, then 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.
This page has 2 threads Add post
walteragwe   Reply to walteragweReply
21 Jan 21 at 02:47

SELECT [AuthorName], COUNT([EpisodeId]) AS [# OF EPISODES],
       MIN([EpisodeDate]) AS [Earliest epi Date],
       max([EpisodeDate]) as [latest epi Date]
FROM   [dbo].[tblAuthor] AS A INNER JOIN [dbo].[tblEpisode] AS E
       ON A.AuthorId = E.AuthorId
GROUP BY [AuthorName]
order by [# OF EPISODES] desc;
GO

shahnawaz   Reply to shahnawazReply
20 Jul 20 at 12:22

select AuthorName, count(EpisodeNumber), EpisodeDate as [Earliest date], EpisodeDate as [Latest date] from 
                                tblAuthor INNER JOIN tblEpisode ON tblAuthor.AuthorId=tblEpisode.AuthorId
                                group by AuthorName, EpisodeDate
                                order by [Earliest date] asc, [Latest date] desc

What is the problem with my code?

Dintakurthi   Reply to DintakurthiReply
19 Nov 20 at 07:27

SELECT a.AuthorName,COUNT(a.AuthorId) AS Episodes,MIN(B.EpisodeDate) AS EarlistDate,MAX(B.EpisodeDate) AS LatestDate from tblAuthor a
INNER JOIN tblEpisode b on b.AuthorId=a.AuthorId 
GROUP BY a.AuthorName,a.AuthorId 
ORDER BY a.AuthorName ASC

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