Comments on: SQL SERVER – Interesting Interview Questions

By: SQL SERVER – Weekly Series – Memory Lane – #008 « SQL Server Journey with SQL Authority

Sat, 22 Dec 2012 01:31:49 +0000

[...] Interview Questions – Revisited Read Interesting Interview Questions before continuing reading this article. This interview question was about user participation and [...]

By: Nikash

Nikash — Mon, 04 Jun 2012 13:44:37 +0000

select ‘student1 has’+ CONVERT(varchar(10), SUM(class1) )+’staudent’
from StudentsEnroll

union all

select ‘student2 has’+ CONVERT(varchar(10), SUM(class2) ) +’staudent’
from StudentsEnroll

union all

select ‘student3 has’+ CONVERT(varchar(10), SUM(class3)) +’staudent’
from StudentsEnroll

By: INDIA

INDIA — Fri, 15 Oct 2010 09:19:44 +0000

thanks pinal for providing good platform for learing
sql

this site very helpful for me

keep it up……

By: INDIA

INDIA — Fri, 15 Oct 2010 09:17:07 +0000

declare @total int
set @total =0
select ‘CLASS 1 HAS ‘ + case when class1=1 then CAST (SUM(@total+1)AS VARCHAR(10)) + ‘ STUDENTS’ end from StudentsEnroll
WHERE Class1 =1
group by Class1
UNION ALL

select ‘CLASS 2 HAS ‘ + case when class2=1 then CAST (SUM(@total+1)AS VARCHAR(10)) + ‘ STUDENTS’ end from StudentsEnroll
WHERE Class2 =1
group by Class2

UNION ALL

select ‘CLASS 3 HAS ‘ + case when class3=1 then CAST (SUM(@total+1)AS VARCHAR(10)) + ‘ STUDENTS’ end from StudentsEnroll
WHERE Class3 =1
group by Class3

By: Lopa

Lopa — Fri, 22 Jan 2010 15:03:00 +0000

Probably I’m asking this doubt very late.

You asked to write a query about student enrollment where there are three classes ; Class1 , Class2 and Class3 and 4 students as Student1, Student2, Student3 and Student4. And there is a table StudentEnroll which has the data which depicts which student is enrolled to which class.

The format of the output should be The Class 1 has 3 students and so on; for all the classes.

You have provided the followin solution

DECLARE @Col INT
SET @Col = 1
WHILE (@Col < 4)
BEGIN
EXEC('SELECT ''Class'+@Col+' Has '' + CAST(COUNT(Students) AS VARCHAR(100)) + '' Students'' Results
FROM studentsenroll
WHERE Class'+@Col+' = 1
GROUP BY Class'+@Col)
SET @Col = @Col + 1
CONTINUE
END

Now, I can understand that you are considering only those students who have been enrolled and that's the reason the class'+@col+' = 1 is a constant value.

This can be easily done by using the Sum function. But, you have mentioned that if the scenario is dynamic then we have to use the Group By function. Could you please explain me the Dynamic scenario.

I'm sorry if I sound stupid.

Regards,
Lopa

By: Pinal Dave

Pinal Dave — Fri, 22 Jan 2010 10:29:27 +0000

Hi Lopa,

In expression class + ‘@col’ what is class and what is value in @col? Please provide details about your query.

Regards,
Pinal Dave

By: Lopa

Lopa — Thu, 21 Jan 2010 23:27:20 +0000

Hi Pinal,

You are doing a great job.

I may sound low, but could you please explain me the where clause of the above query. Why the class+’@col’ value is always constant?

Thanks,
Lopa

By: Sandor

Sandor — Fri, 04 Dec 2009 19:44:38 +0000

How about this:

select classname + ‘ has ‘ + Cast(total As Nvarchar(2)) + ‘ students’ from
(
select
sum(class1) class1,
sum(class2) class2,
sum(class3) class3
from studentsenroll
) p
unpivot
( Total for classname in (class1,class2,class3)) as S

By: RakeshA

RakeshA — Mon, 21 Sep 2009 17:19:24 +0000

create table xs(sname nvarchar(5),class1 int,class2 int,class3 int)

insert into xs values(‘stu1′,1,0,1)
insert into xs values(‘stu2′,1,0,1)
insert into xs values(‘stu3′,0,1,0)
insert into xs values(‘stu4′,1,0,1)

select sname+’has ‘+ cast((class1+class2+class3) as nvarchar(10))+’students’ from xs

By: Kode

Kode — Wed, 10 Jun 2009 09:14:28 +0000

declare @count int
declare @name varchar(30)
declare @stmt nvarchar(500)
set @stmt = ”
select @count = count(*) from sys.columns where object_id = object_id(‘studentsenroll’) and name ‘Students’
Declare c1 cursor
For select Name From sys.columns where object_id = object_id(‘studentsenroll’) and name ‘Students’
Open c1
fetch next from c1 into @name
while @@fetch_status = 0
Begin
if ( @count > 1)
set @stmt = @stmt + ‘select ”’ + @name + ‘ has ” + cast(sum(cast(‘ + @name + ‘ as int)) as varchar) +” students ” From studentsenroll union all ‘
else
set @stmt = @stmt + ‘select ”’ + @name + ‘ has ” + cast(sum(cast(‘ + @name + ‘ as int)) as varchar) +” students ” From studentsenroll ‘
SET @count = @count-1
fetch next from c1 into @name
End
exec sp_executesql @stmt
close c1
deallocate c1

By: Anu

Anu — Tue, 19 May 2009 11:46:53 +0000

Hi Pinal,
This place is really gud for all the issues related to sql.
I just saw the query above so just tried this way

select ‘Class1 has ‘ + cast(count(nullif(class1,0))as varchar(10)) +’ students’ from StudentsEnroll union
select ‘Class2 has ‘+ cast(count(nullif(class2,0))as varchar(10)) + ‘ students’ from StudentsEnroll union
select ‘Class3 has ‘+cast(count(nullif(class3,0))as varchar(10)) +’ students’from StudentsEnroll

Its the same way as you have written i have just modified the query by using NULLIF so where clause would’nt be used.

By: Jerry

Jerry — Mon, 05 Jan 2009 07:14:04 +0000

Hi Pinal,

I am a beginner in SQL can you please give me suggestion as to how i can improve on it?.
I am very much interested in learning SQL Server.

Thanks,
Jerry

By: meh

meh — Thu, 18 Dec 2008 21:04:43 +0000

SELECT
UP.Class + ‘ has ‘ + CONVERT(varchar, SUM(CONVERT(int, UP.Total))) + ‘ Students’ [Output]
FROM
(
SELECT
Students [Enrolled],
Class1,
Class2,
Class3
FROM
StudentsEnroll
) SE
UNPIVOT (Total FOR Class IN (Class1, Class2, Class3)) UP
GROUP BY
UP.Class

By: cvdev

cvdev — Wed, 17 Dec 2008 20:51:57 +0000

SELECT ‘Class1 Has ‘+CAST(SUM(CAST(Class1 AS INT)) AS VARCHAR(10))+’ Students’+CHAR(10)+
‘Class2 Has ‘+CAST(SUM(CAST(Class2 AS INT)) AS VARCHAR(10))+’ Students’+CHAR(10)+
‘Class3 Has ‘+CAST(SUM(CAST(Class3 AS INT)) AS VARCHAR(10))+’ Students’+CHAR(10)
FROM [StudentsEnroll]

By: Harshal

Harshal — Wed, 17 Dec 2008 11:13:48 +0000

SELECT ‘Class1 has ‘+ CONVERT(nvarchar(10),sum(CASE class1 WHEN 1 THEN 1 ELSE 0 end))+’ students’
FROM StudentsEnroll se union ALL
SELECT ‘Class2 has ‘+ CONVERT(nvarchar(10),sum(CASE class2 WHEN 1 THEN 1 ELSE 0 end))+’ students’
FROM StudentsEnroll se union ALL
SELECT ‘Class3 has ‘+ CONVERT(nvarchar(10),sum(CASE class3 WHEN 1 THEN 1 ELSE 0 end))+’ students’
FROM StudentsEnroll se

By: SQL SERVER - Interesting Interview Questions - Revisited Journey to SQL Authority with Pinal Dave

Wed, 17 Dec 2008 01:30:29 +0000

[...] Zod [...]

By: jagadesh

jagadesh — Thu, 11 Dec 2008 14:44:12 +0000

hi pinal,
I am a beginner in sql server…can u give me any suggestions in his regard..

Thanks
Jagadesh

By: jagadesh

jagadesh — Thu, 11 Dec 2008 14:40:17 +0000

hi i am new to sql server and its very intresting to see such good questions.
i would participate int hese discussions and post my comments for the queries.

Thanks
jagadesh

By: mumu

mumu — Thu, 11 Dec 2008 04:45:24 +0000

Imran is correct in that PIVOT is not the answer (as surmised) but UNPIVOT.

Here’s a bit cleaner version of UNPIVOT that is closer to the asked for end result…

SELECT Class,
CAST(‘has’ as char(3)) as ‘has’,
SUM(CAST(Breakout as tinyint)) as ‘X’,
CAST(‘students.’ as char(9)) as ‘students.’
FROM (

SELECT Class, Breakout, Students FROM
(
SELECT Students, Class1, Class2, Class3
FROM StudentsEnroll
) se_inner
UNPIVOT (Breakout FOR Class IN (Class1, Class2, Class3)) AS denorm
) se_outer
GROUP BY Class ORDER BY Class

By: pinaldave

pinaldave — Wed, 10 Dec 2008 20:06:23 +0000

Guys, this is great participation from all of you, I will be writing in depth another article where I will have all this answers included.

Keep up the good work.

If you are interested participate in second question :
http://blog.sqlauthority.com/2008/12/10/sql-server-interesting-interview-questions-part-2-puzzle/

Regards,
Pinal Dave ( http://blog.sqlauthority.com )

By: Prabhat

Prabhat — Tue, 09 Dec 2008 18:14:41 +0000

Thanks for the nice tricks.

By: pom

pom — Tue, 09 Dec 2008 06:01:07 +0000

select ‘class1 has ‘ + cast((select count(*) from StudentsEnroll where class1=1 group by class1) as char(3)) + ‘Students’
union
select ‘class2 has ‘ + cast((select count(*) from StudentsEnroll where class2=1 group by class2) as char(3)) + ‘Students’
union
select ‘class3 has ‘ + cast((select count(*) from StudentsEnroll where class3=1 group by class3) as char(3)) + ‘Students’

By: SQL SERVER - Find Table Rowcount Without Using T-SQL and Without Opening Table Journey to SQL Authority with Pinal Dave

Tue, 09 Dec 2008 01:31:29 +0000

[...] December 9, 2008 by pinaldave Recently I have been busy with interviewing many candidates for my organization. We are looking for some smart and experienced developers for some senior positions. I have wrote this previously SQL SERVER – Interesting Interview Questions. [...]

By: Prakash

Prakash — Mon, 08 Dec 2008 16:11:40 +0000

Hi all,
Good to see you here and very very thanks for sharing the knowledge.

So anyone can u please tell me about the difference between table variables and the cursors..

which is good one and where??

Thanks
Regards Prakash

By: pinaldave

pinaldave — Mon, 08 Dec 2008 09:32:57 +0000

Dear Readers,

Take this question as T-SQL practice exam rather than schema improvement problem.

In my organization we do not ask this simple question for Schema improvement. Normalization is important but in data warehousing and BI de-normalization is equally important.

Hope this clear now and waiting for more T-SQL solution to this problem.

Everybody who participated here – Thanks I really see good suggestions.

Kind Regards,
Pinal Dave