SQL | Aggregation and grouping exercise | Show the total number of events for each century

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 ==> Aggregation and grouping  (8 exercises)
Level ==> Harder than average
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). Once you've done this:
  1. Go into SQL Server Management Studio;
  2. Open the SQL file you've just unzipped (you can press CTRL + O to do this); then
  3. Execute this script.

This will generate the database that you'll need to use in order to do this exercise (note that the database and script are only to be used for exercises published on this website, and may not be reused or distributed in any form without the prior written permission of Wise Owl).

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.

Create a query to show the following information:

Events by century

You'll need to calculate the century for each event date, and group by this.

 

To get the top row giving the grand total in the same query, encase your GROUP BY expression in the CUBE function.

Save this query as Passing of the centuries, then close it down.

This page has 1 thread Add post
linjom   Reply to linjomReply
23 Apr 18 at 07:33

I am getting different result.. 

NULL    459
18th Century    4
19th Century    14
20th Century    396
21st Century    45

for both rollup and cube.. is this right? Final total same as site.

 

Zerish   Reply to ZerishReply
22 May 18 at 05:43

This will give you exact same result as posted on site 

USE WorldEvents
GO

SELECT 
CASE 
WHEN DATEPART(YY,tblEvent.EventDate) like '18%' THEN '19th Century'
WHEN DATEPART(YY,tblEvent.EventDate) like '17%' THEN '18th Century'
WHEN DATEPART(YY,tblEvent.EventDate) like '19%' THEN '20th Century'
WHEN DATEPART(YY,tblEvent.EventDate) like '20%' THEN '21st Century'
END AS Century,COUNT(tblEvent.EventName) AS NumberOfEvents
FROM tblEvent
GROUP BY CUBE(CASE 
WHEN DATEPART(YY,tblEvent.EventDate) like '18%' THEN '19th Century'
WHEN DATEPART(YY,tblEvent.EventDate) like '17%' THEN '18th Century'
WHEN DATEPART(YY,tblEvent.EventDate) like '19%' THEN '20th Century'
WHEN DATEPART(YY,tblEvent.EventDate) like '20%' THEN '21st Century'
END)
ORDER BY NumberOfEvents DESC

Add a new post