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SQL | Variables exercise | Retrieve aggregated data using variables
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!
- Go into SQL Server Management Studio;
- Open the SQL file you've just unzipped (you can press CTRL + O to do this); then
- 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).
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The aim of this exercise is to summarise events using the MIN, MAX and COUNT functions:
The snag? You're not allowed to use GROUP BY!
To do this, create variables to hold each of the aggregates:
|Variable||What it will hold eventually|
|@EarliestDate||The earliest date|
|@LatestDate||The latest date|
|@NumberOfEvents||The number of events|
|@EventInfo||The title Summary of events|
Now use a single SELECT clause to set the value for all of these variables (alternatively you could use a series of subqueries).
Write another SELECT clause to show the value of the variables, to show the summary output shown above.
Optionally save this as The early, the late and the rest.sql and close it down.
I'm having trouble getting this exercise done.
Is there anywhere i can get the solution?
declare @EarliestDate datetime
declare @latestDate datetime
declare @NoOfEvents int
declare @Eventimfo varchar(max)='Summary of event'
select @EarliestDate=min( cast(EventDate as date)) from dbo.tblEvent
select @latestDate=max(cast(EventDate as date)) from dbo.tblEvent
select @NoOfEvents=count(EventID) from dbo.tblEvent
select @Eventimfo as Title, @EarliestDate as EarliestDate,@latestDate as latestDate,@NoOfEvents as NoOfEvents
We don't post the answers to exercises (as you'll have noticed) - partly because there has to be some reason to attend our courses, but also because it would remove the incentive to work at finding a solution. For the same reasons we usually don't post prospective answers, but since you ask nicely ... anyone out there able to help and post a solution?