Comments on: SQL SERVER – Interesting Interview Questions

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

By: John

John — Mon, 08 Dec 2008 09:06:34 +0000

I’d be concerned about any organisation that asked a question like that. The table design is terrible, and if it was more normalized, there wouldn’t be any need to come up with clever solutions.

Of course, if the question asked how you would improve the schema and then return the output that would be acceptable.

By: fly

fly — Mon, 08 Dec 2008 07:48:44 +0000

How about this:

declare @tbl table (i int)
insert into @tbl (i)
select 1
union
select 2
union
select 3

select
case when i = 1 then ‘Class 1 has ‘ + cast(sum(cast (class1 as int)) as varchar(100)) + ‘ Students’ else
case when i = 2 then ‘Class 2 has ‘ + cast(sum(cast (class2 as int)) as varchar(100)) + ‘ Students’ else
case when i = 3 then ‘Class 3 has ‘ + cast(sum(cast (class3 as int)) as varchar(100)) + ‘ Students’ else ” end
end
end
from [StudentsEnroll]
join @tbl t on i <= 3
group by i

By: bhadeliaimran

bhadeliaimran — Mon, 08 Dec 2008 06:06:49 +0000

DECLARE @opXml as XML

SET @opXml = ‘ (SELECT
‘Class1 has ‘ + CAST(SUM(CAST(Class1 AS SMALLINT)) AS VARCHAR(4)) + ‘ students’ ,
‘,Class2 has ‘ + CAST(SUM(CAST(Class2 AS SMALLINT)) AS VARCHAR(4)) + ‘ students’ ,
‘,Class3 has ‘ + CAST(SUM(CAST(Class3 AS SMALLINT)) AS VARCHAR(4)) + ‘ students’
FROM [StudentsEnroll]
FOR XML PATH(”) ), ‘,’, ‘” />’

SELECT x.value(‘@value’, ‘varchar(100)’) AS [output]
FROM @opXml.nodes(‘/ClassStud’) as p(x)