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SQL | Subqueries exercise | Show countries with more than 8 events, using a subquery
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.
Software ==> | SQL (198 exercises) |
Version ==> | Any version of SQL Server |
Topic ==> | Subqueries (5 exercises) |
Level ==> | Average difficulty |
Subject ==> | SQL training |
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Write a query which lists out countries which have more than 8 events, using a correlated subquery rather than HAVING.
That is: list the names of countries from the countries table where for each country the number of events matching the country's id is more than 8.
If you list the countries in alphabetical order, you should get:

Although your query should be easy to read, one disadvantage is that you can't see how many events there were for each country.
Save this query as Eventful countries, then close it down.
SELECT CountryName
FROM tblCountry INNER JOIN tblEvent
ON tblCountry.CountryID = tblEvent.CountryID
GROUP BY CountryName
HAVING COUNT(tblEvent.EventID) > 8
This Query Works fine.
Need not to write Sub-Query
with cte1 as
(
select c.countryname,(select COUNT(e.countryid)
from tblEvent e
where e.CountryID = c.CountryID
group by e.countryid) as noocc
from tblcountry c)
select CountryName from cte1 where noocc>8
This is also a perfect output:
SELECT A.CountryName
FROM TblCountry A
INNER JOIN
(
SELECT TE.CountryID, COUNT(TE.EventID) XYX
FROM tblEvent TE
GROUP BY TE.CountryID HAVING COUNT(TE.EventID) > 8) B ON A.CountryID = B.CountryID
)
We can get the country name and no of event occured without even using a subquery:
select distinct count([EventName]) as No_of_event,[CountryName] from [tblEvent] e
inner join [dbo].[tblCountry] c on e.CountryID = c.CountryID
group by [CountryName]
having count([EventName]) >8
Not a big deal to show also the numbers of events per country:
select c.CountryName , (select count(*) from tblEvent where CountryID = C.CountryID) [Number of events]
from tblCountry c
Couldn't do it without using HAVING in the subquery :-(
Anyone has any ideas?
DISTINCT cntr.CountryName
FROM
tblEvent evnt
INNER JOIN tblCountry cntr
ON evnt.CountryID = cntr.CountryID
WHERE evnt.CountryID IN
--countryID for countries that has more than 8 events
(
SELECT
evnt.CountryID
--,count(evnt.EventID) AS [Number of events]
FROM
tblEvent evnt
INNER JOIN tblCountry cntr
ON evnt.CountryID = cntr.CountryID
GROUP BY
evnt.CountryID,
cntr.CountryName
Having
count(evnt.EventID) > 8
)
Hi,
Looks like this is working:
SELECT
c.CountryName
FROM
tblCountry c
WHERE
8 < (
SELECT
COUNT(e.EventID)
FROM
tblEvent e
WHERE
e.CountryID = c.CountryID
)
Order By
c.CountryName;