Interview question on SQL.........

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I have been asked a quetion in Interivew

FIleID FileName IsValid
1 A 0
2 B 0
3 C 1
4 D 0

So question is that in above table column isValid can contain any numeric value ranging from 0 to infinity.Means it can have 100,200 likewise

so if that column don't have same value throughout then query should return false else true

without using join or where condition

What I have tried:

I am trying to create a function but this also not required

Posted 2-Sep-17 2:37am

vivvicks

Updated 5-Sep-17 21:23pm

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Comments

CPallini 2-Sep-17 9:04am

Could you please elaborate?

vivvicks 2-Sep-17 9:13am

means if value in isValid columns are same then it shd return true else false
it shd like
0
0
0
0
is true
0
1
0
0
is false
but we dont know the what value will be there

3 solutions

Solution 2

Try this:

IF (SELECT COUNT(*) FROM tablename) = (SELECT COUNT(DISTINCT column_of_interest) FROM tablename)
   SELECT 'FALSE'
ELSE
   SELECT 'TRUE'

Posted 2-Sep-17 3:03am

Peter Leow

Comments

CPallini 2-Sep-17 9:15am

5.Possibly GROUP BY could be an alternative.

vivvicks 2-Sep-17 9:22am

hum..but it shd have only select.and above is not working as expected

Peter Leow 2-Sep-17 9:50am

It's the "thought" that counts.

vivvicks 2-Sep-17 10:33am

yes Sir..Thanks for reply

Peter Leow 2-Sep-17 9:49am

Thank you, CPallini.

Solution 1

We do not do your homework: and interviews are homework! They are there so the company can get an idea of your skills and assess if you fit into their team, and can do the job - not if I do and can. If we do it for you, that isn't fair on anybody: the company because interviewing is a very expensive business, the other applicants who could do the task and presumably the job, and ultimately you - because once the company finds out you lied on the interview you won't last long in the job either.

Try it yourself, you may find it is not as difficult as you think!

Posted 2-Sep-17 2:49am

OriginalGriff

Comments

vivvicks 2-Sep-17 8:56am

Interview is done.Some forums reply with answer that is why i put it here i guess i have paste in wrong forum.

Dave Kreskowiak 2-Sep-17 11:35am

Sure, you're going to get queries that will show you the answer to the question, but you're not going to know WHY it works and that's the entire point of the question in the interview.

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Wendelius · Accepted Answer · 2017-09-02T04:05:00

Solution 3

Not sure if I understand the question correctly, but try the following:

SQL

select
   case (select count(*) 
         from (select distinct isValid 
		       from TableName) a)
      when 1 then 'True'
      else 'False'
   end

Posted 2-Sep-17 4:05am

Wendelius