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Software ==>	SQL (203 exercises)
Topic ==>	Calculations (18 exercises)
Level ==>	Harder than average
Subject ==>	SQL training

Use the % modulus operator and a lot of ingenuity to show how big each country is relative to Wales

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 . Once you've done this:

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).

First open the script in the folder above and execute it - you should now be looking at a list of the world's countries.

It's traditional to express a country's size in terms of how many times you could fit Wales into it - so let's do this! First create the following columns in a query:

Column	What it should show
AreaLeftOver	The remainder when you divide a country's area by the area of Wales
WalesUnits	The number of exact times that the area of Wales divides a country's area, once you've subtracted the area left over as calculated above

You'll need to know that Wales is 20,761 square kilometres in area!

Now extend your query to show a text description of how many times each country could accommodate Wales:

The first few countries in alphabetical order.

Finally, change your query's sort order so that it lists countries with the closest in size to Wales first:

El Salvador is closest in size to Wales, followed by Slovenia (the first is slightly larger, the second slightly smaller).

You may find the ABS function useful to show the absolute value of the difference in sizes for each country. If you're wondering why Wales isn't top of the list ... it's not a country in its own right!

Save this query as How many whales, 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.

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

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From:	Chinmaykumar
When:	02 Jul 23 at 00:10

Query_Sol. for MySQL users

SELECT
Country,
KmSquared,

/* In MySQL, you can use the 'DIV' to perform integer division in a SELECT statement */
(KmSquared DIV 20761) AS WalesUnits,

/* To find the remainder of division use '%' (modulo) operator. Ex: 10 % 3 is 1 */
   (KmSquared % 20761) AS AreaLeftOver,

   CASE
       WHEN
           (KmSquared DIV 20761) > 0
       THEN
           CONCAT((KmSquared DIV 20761),' x Wales plus ',(KmSquared % 20761),' sq. km.')
       ELSE 'Smaller than Wales'
   END AS WalesComparison
FROM
   countriesbyarea

/* Important: To sort column by the specific nearest values to the specific value
use 'ABS(column_name - target_value)' */
ORDER BY ABS(KmSquared - 20761);

From:	Aravindh_sql
When:	26 May 22 at 07:42

SELECT Country,
KmSquared,
KmSquared/20761 as WalesUnits,
(KmSquared)-(KmSquared/20761)*20761 as AreaLeftOver,
CASE
       WHEN KmSquared < 20761 THEN 'Smaller than Wales'
ELSE
       CONCAT(
KmSquared/20761, 'x', ' Wales Plus ',' ' ,
(KmSquared)-(KmSquared/20761)*20761 ,' ','Sq.km'
)

END as WalesComparision

FROM CountriesByArea
ORDER BY ABS(20761-KmSquared) ASC

From:	MalaMi
When:	14 Jun 21 at 22:44

SELECT Country,
       KmSquared,
       KmSquared % 20761 AS AreaLeftOver,
       (KmSquared - (KmSquared % 20761))/20761 AS WalesUnits,
       CONCAT((KmSquared - (KmSquared % 20761))/20761, ' x Wales plus ', KmSquared % 20761, ' sq. km.') AS WalesComparison
FROM CountriesByArea
ORDER BY ABS(20761 - KmSquared) ASC

From:	SeahawkZim
When:	16 Mar 20 at 22:58

In the SQL script used to design and fill the CountriesByArea table, there is no entry for Wales.

From:	Andy B
When:	17 Mar 20 at 09:54

There doesn't need to be! You can assess how close in area a country is to Wales without including Wales in your list of countries.

From:	SeahawkZim
When:	17 Mar 20 at 14:55

Yeah, I saw that after I posted my comments. I tried to delete the comments, but I did not see that as an option. Thanks for posting a reply regardless.

From:	hjay629
When:	18 Feb 19 at 23:28

--SPOILER--

ANSWER:

SELECT
Country
, KmSquared
, ROUND(KmSquared/20761, 0) as 'WalesUnits'
, (Kmsquared % 20761) as 'AreaLeftOver'
, CASE
WHEN
CAST(ROUND((KmSquared/20761), 0) as varchar(10)) < 1
THEN
'Smaller than Wales'
ELSE
CAST(ROUND((KmSquared/20761), 0) as VARCHAR(10)) + ' x ' + ' Wales plus ' +
CAST( (KmSquared % 20761) as VARCHAR(10)) + ' sq. km.'
END as 'Wales Comparison'
FROM
CountriesByArea
Order By ABS(KmSquared - 20761)

From:	chaluvadi
When:	07 Sep 18 at 17:05

if i have array of numbers

10, 9.8, 10.1, 9.5, 10.8, 9.7

I would like to arrange this array by nearest to 10.

To compare this array to 10. I am going to subtract array values from 10:

(10-10), (10 - 9.8), (10-10.1), (10-9.5), (10-10.8), (10-9.7)

0, 0.2, -0.1, 0.5, -0.8, 0.3

To compare numbers i have to consider both postives and negatives, so i am going to use absolute values

0, 0.2, 0.1, 0.5, 0.8, 0.3

Now let's arrange these numbers nearest to 10:

0, 0.1, 0.2, 0.3, 0.5, 0.8

Now write down with corresponding numbers:

10, 10.1, 9.8, 9.7, 9.5, 10.8

So to summarize, i arranged numbers by using ABS(MyNumbers - 10)

From:	gemini132
When:	13 Aug 18 at 13:12

I managed to get until the last part but still when sorting the results as requested the are two countries misssing, any ideas on the tweak that needs to be done to the query to get these two counties listed?

SELECT Country
,KmSquared
,ABS(KmSquared/20761) AS WalesUnits
,ABS(KmSquared)-((KmSquared/20761)*20761) AS AreaLeftOver
,CASE
WHEN KmSquared > 20761 THEN CAST(KmSquared/20761 AS VARCHAR(20))
+ ' x ' + 'Wales plus' + ' ' + CAST((KmSquared)-((KmSquared/20761)*20761
) AS VARCHAR(25)) + ' ' + 'sq. km.'
WHEN KmSquared <= 20761 THEN 'Smaller than Wales'
END AS WalesComparison
FROM CountriesByArea
WHERE kmSquared <= ALL (SELECT KmSquared
FROM CountriesByArea
WHERE ABS(20761 - KmSquared) < 500)

From:	DataDriven
When:	18 Jun 18 at 23:43

Can anyone help me with the query for text description of how many times each country could accommodate Wales?

From:	linjom
When:	17 Apr 18 at 13:17

I could solve till the second last requirement. The final one seems tough .... can anyone help with the trick?

From:	morguel
When:	22 Apr 18 at 08:49

Hi,

at the first look it seems though, but it is quite simple. You want to order by KmSquared ascending in the near of Wales (size=20761). So what if Wales itself would be in the list? It's KmSquared would be 20761. The difference WalesSize-20761=0 the next greater one could be (WalesSize+x)-20761=x ans so on...
But what about the smaler ones? Same thoughts. And here comes ABS function in play to get rid of the minus...Clear now? Or do u want the result?

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SQL EXERCISES

Use the % modulus operator and a lot of ingenuity to show how big each country is relative to Wales

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