Comments on: SQL SERVER – Interesting Interview Questions – Revisited

By: Ubaid Shahid

Ubaid Shahid — Tue, 18 Oct 2011 17:44:01 +0000

Declare @totClass TinyInt
Declare @sqlQuery NVarchar(Max)=”
Select @totClass=IsNull(COUNT(*),0) From sys.columns
where object_id=object_id(‘studentsample’) and name like ‘class%’

While(@totClass>=1)
Begin
Set @sqlQuery=@sqlQuery+’Select ”Class”+Convert(varchar(2),’+Convert(Varchar(2),@totClass)+’)+” has total ”
+CONVERT(varchar(3),sum(Class’+Convert(Varchar(2),@totClass)+’))+ ” students” From studentSample’

If(@totClass1)
Begin
Set @sqlQuery=@sqlQuery+’ Union All ‘
End
Set @totClass=@totClass-1

End
Exec(@sqlQuery)

By: Ubaid Shahid

Ubaid Shahid — Tue, 18 Oct 2011 17:33:44 +0000

–[Note] I am using SQL Server Version 2008

Declare @totClass TinyInt
Declare @sqlQuery NVarchar(Max)=”
Select @totClass=IsNull(COUNT(*),0) From sys.columns
where object_id=object_id(‘studentsample’) and name like ‘class%’

If(@totClass1)
Begin
Set @sqlQuery=@sqlQuery+’ Union All ‘
End
Set @totClass=@totClass-1

End
Exec(@sqlQuery)

By: vipul

vipul — Thu, 14 May 2009 08:41:28 +0000

Helllo Sir
MY self vipul and i want to knw how we got Row number in MSSQLSERVER2005 and how we use custom paging in select statement ……….
Reply me on my mail it ………

By: jing

jing — Wed, 21 Jan 2009 16:35:58 +0000

Solution by Imran Mohammed

SELECT CLASS+ ‘ has ’+CONVERT(VARCHAR(10),COUNT(orders ))+‘ Students ’ ’Output’ FROM (
SELECT students, Class, Orders
FROM
(SELECT students, class1, class2,class3
FROM studentsenroll ) p
UNPIVOT
(Orders FOR Class IN
(class1, class2, class3 )
)AS unpvt) X WHERE orders = 1 GROUP BY class

My favor solution is above one, the reason is for better performance, execute this query only require 1 table scan count and 1 logical reads.

By: zlika

zlika — Wed, 17 Dec 2008 11:04:51 +0000

USE DATABASE
GO

SELECT ‘Class1 has ‘ + CAST(COUNT(Class1) AS VARCHAR(10)) + ‘ students.’
FROM StudentsEnroll
WHERE Class1 = ‘True’
UNION ALL
SELECT ‘Class2 has ‘ + CAST(COUNT(Class2) AS VARCHAR(10)) + ‘ students.’
FROM StudentsEnroll
WHERE Class2 = ‘True’
UNION ALL
SELECT ‘Class3 has ‘ + CAST(COUNT(Class3) AS VARCHAR(10)) + ‘ students.’
FROM StudentsEnroll
WHERE Class3 = ‘True’
GO

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Best wishes