Top 100 SQL server queries Interview questions | SQL server interview questions

Introduction

In this article, you will find basic to most puzzled interview queries questions with an example. This article is very useful for those who are preparing for an interview in IT company. Whether you are experienced or fresher, this article will cover all Microsoft SQL server interview questions from basic to advanced level.

So, before starting let’s create and populate tblstudent and tblScholarship table using following script.

Create table tblStudent
(
    StudentId int,
    FirstName varchar(50),
    LastName varchar(50),
    Admission_fee int,
    Admission_date datetime,
    Branch varchar(50),
)
Create table tblScholarship
(
    Student_ref_id int,
    Scholarship_Date date,
    Scholarship_Amount int
)

SQL Server Basic Questions – ‘Select’, ‘Where’, ‘Order By’, ‘Wild Card Search’.

1) Get all students details from the tblstudent table.

Select * from tblstudent

2) Get first name from the tblstudent using alias name “StudentName”.

Select FirstName as StudentName from tblstudent

3) Get first name, last name from the tblstudent table.

Select FirstName, LastName from tblstudent

4) Select student details whose name is “David” from tblstudent.

Select * from tblstudent where FirstName = 'David'

5) Get first name from tblstudent in upper case.

Select upper(FirstName) from tblstudent 

6) Get last name from tblstudent in lower case.

Select lower(FirstName) from tblstudent 

7) Get unique branch from tblstudent table.

Select distinct(Branch) from tblstudent

 Also check, Top C# interview questions and answers

8) Write a query to combine FirstName and LastName and display it as “Full Name”.

Select FirstName +' '+ LastName As "Full Name" from tblstudent 

9) Get all student details from tblstudent whose “FirstName” contains ‘a’.

Select * from tblstudent where FirstName like '%A%'

10) Get all student details from tblstudent whose “FirstName” start with latter ‘d’.

Select * from tblstudent where FirstName like 'D%'

11) Get all student details from tblstudent whose “FirstName” end with ‘a’.

Select * from tblstudent where FirstName like '%a'

12) List all students whose first name start with ‘Ma’ or ‘Da’.

SELECT FirstName, LastName, Branch FROM tblStudent WHERE firstname LIKE '%Ma%' OR firstname LIKE '%Da%'

13) Get all students details from the tblStudent table order by FirstName Ascending.

Select * from tblStudent order by FirstName asc

14) Get all students details from the tblStudent table order by FirstName Descending

Select * from tblStudent order by FirstName desc

15) Get all students details from the tblStudent table order by LastName Ascending and Admission fees descending.

Select * from tblStudent order by LastName asc, Admission_Fee desc

16) Get position of ‘v’ in name ‘David’ from tblstudent.

Select CHARINDEX('v', FirstName,0) from tblstudent where FirstName = 'David'

17) Select firstname from tblstudent with ‘Hello’ prefix.

select 'Hello ' + firstname from tblStudent

18) Get FirstName from tblstudent after removing white spaces from right side.

Select RTRIM(FirstName) from tblstudent

19) Get FirstName from tblstudent after removing white spaces from left side.

Select LTRIM(FirstName) from tblstudent

20) Get length of FirstName from tblstudent.

Select len(FirstName) from tblstudent

21) Get FristName from tblStudent table after replacing ‘a’ with ‘$’.

Select REPLACE(FirstName,'a','$') from tblStudent

22) Get all students details from tblStudent whose first name starts with ‘m’ and name contains 4 letters.

Select * from tblStudent where FirstName like 'm___'

23) Get all students details from tblStudent whose first name ends with ‘a’ and name contains 4 letters.

Select * from tblStudent where FirstName like '___a' 

24) Get fristname from tblstudent not start with any single character between a-p.

select * from tblStudent where FirstName like '[^a-p]%'

SQL Server Advanced Questions – ‘DateTime’

25) Get first name, admission year, admission month and admission date from tblStudent table.

select SUBSTRING (convert(varchar,admission_date,103),7,4) as Year,
SUBSTRING (convert(varchar,admission_date,100),1,3) as Month, 
SUBSTRING (convert(varchar,admission_date,100),5,2) as Date
from tblStudent

26) Get student details from tblStudent table whose admission year is “2015”.

Select * from tblStudent where SUBSTRING(convert(varchar,Admission_date,103),7,4)='2015'

27) Get student details from tblStudent table whose admission date is after January 31st.

Select * from tblStudent where Admission_date >'01/31/2016'

28) Get student details from tblStudent table whose admission date is before January 31st.

Select * from tblStudent where Admission_date <'01/31/2016'

29) Get student details from tblStudent table whose admission month is “January”.

Select * from tblStudent where SUBSTRING(convert(varchar,Admission_date,100),1,3)='Jan'

30) Get admission date and time from tblStudent table.

Select convert(varchar(19), admission_date,121) from tblStudent

31) Get database date.

select getdate()

32) Get UTC date.

select GETUTCDATE()

33) Get only month part of admission date from tblStudent.

select DATEPART(MONTH, admission_date) from tblStudent

34) Get only year part of admission date from tblStudent.

select DATEPART(YEAR, admission_date) from tblStudent

35) Get all student details from tblStudent table whose admission date between ‘2015-01-01’ and ‘2016-01-01’.

select * from tblStudent where admission_date between '2015-01-01' and '2016-01-01'

36) Get the first name, last name, current date, admission date and difference between current date and admission date in days.

select FirstName, LastName, GETDATE() as 'Current_date', Admission_date,
DATEDIFF(DD, Admission_date, GETDATE()) As days from tblStudent

37) Get the first name, last name, current date, admission date and difference between current date and admission date in month.

select FirstName, LastName, GETDATE() as 'Current_date', Admission_date,
DATEDIFF(MM, Admission_date, GETDATE()) As months from tblStudent

Also check, Top C# interview questions and answers

38) Get the first name, last name, current date, admission date and difference between current date and admission date in year.

select FirstName, LastName, GETDATE() as 'Current_date', Admission_date,
DATEDIFF(YYYY, Admission_date, GETDATE()) As years from tblStudent

39) Show “AdmissionDate” in “dd mmm yyyy” format, ex- “06 May 2016”.

select CONVERT(varchar(30), admission_date, 106) from tblStudent

40) Show “AdmissionDate” in “yyyy/mm/dd” format, ex- “2016/05/06”.

select CONVERT(varchar(30), admission_date, 111) from tblStudent

41) Show only time part of the “AdmissionDate” from tblStudent.

Select CONVERT(varchar(20), admission_date, 108) from tblStudent

42) Select no of students get admission with respect to year and month from tblStudent table.

select datepart (YYYY,Admission_date) Admission_Year, datepart (MM,Admission_date)
Admission_Month,count(*) Total_Student from tblStudent group by datepart(YYYY,Admission_date),
datepart(MM,Admission_date)

SQL Server Advanced Questions – ‘Top, Union, admission fees and Group by’ questions

43) Select TOP Nth (any number) admission fees from tblStudent table

select top 1 * from tblStudent

44) Select second highest admission fees from “tblStudent” table.

Select TOP 1 Admission_fee from (Select TOP 2 Admission_fee from tblStudent
order by Admission_fee DESC) T Order By Admission_fee ASC

45) Select TOP 2 Admission fees from tblStudent table

select top 2 * from tblStudent order by Admission_fee desc

46) Select Highest Admission fees from tblStudent table.

Select Max(Admission_fee) from (select top 6 * from tblStudent) A

47) Select Minimum Admission fees from tblStudent table.

Select Min(Admission_fee) from (select top 6 * from tblStudent) A

48) Select FirstName, LastName from tblStudent table in singal column.

select FirstName from tblStudent union select LastName from tblStudent

49) Get students details from “tblStudent” table whose admission fees is less than 15000.

Select * from tblStudent where Admission_fee < 15000

50) Get students details from “tblStudent” table whose admission fees is greater than 15000.

Select * from tblStudent where Admission_fee > 15000

51) Get students details from “tblStudent” table whose admission fees in between 10000 and 15000.

Select * from tblStudent where Admission_fee between 10000 and 15000

52) Select 5 % of admission fees from sara , 10% of admission fees from Dora and for other 15 % of admission fees as ‘Deducted_Admission_fee’ from tblStudent table.

SELECT FirstName, CASE FirstName WHEN 'Sara' THEN Admission_fee * .10 WHEN 'Dora' THEN Admission_fee * .15 ELSE Admission_fee * .15

53) Write a query to get how many students exist in tblstudent.

select COUNT(*) from tblStudent

54) Write the query to get the branch and branch wise total(sum) admission fees, display it in ascending order according to admission fees.

Select Branch, SUM(admission_fee) as Total_admission_fees from tblStudent
group by Branch order by SUM(admission_fee) ASC

55) Write the query to get the branch and branch wise total(sum) admission fees, display it in desending order according to admission fees.

Select Branch, SUM(admission_fee) as Total_admission_fees from tblStudent
group by Branch order by SUM(admission_fee) DESC

56) Get branch wise average admission fees from “tblStudent” table order by admission fees ascending order.

Select Branch, AVG(admission_fee) as Average_admission_fees from tblStudent
group by Branch order by SUM(admission_fee) ASC

57) Get branch wise maximum admission fees from “tblStudent” table order by admission fees descending order.

Select Branch, MAX(admission_fee) as Maxmum_admission_fees from tblStudent
group by Branch order by SUM(admission_fee) DESC

58) Get branch wise minimum admission fees from “tblStudent” table order by admission fees ascending order.

Select Branch, MIN(admission_fee) as Minimum_admission_fees from tblStudent
group by Branch order by SUM(admission_fee) ASC

59) Get branch, no of students in a branch, total admission fees with respect to a branch from tblStudent table order by admission fees descending.

Select Branch,count(FirstName),sum(admission_fee) Admission_fee from tblStudent
group by Branch order by Admission_fee desc

60) Select no of students joined with respect to year and month from tblStudent table.

select datepart (YYYY,Admission_date) Admission_year,datepart (MM,Admission_date) Admission_month,
count(*) Total_student from tblStudent group by datepart(YYYY,Admission_date), datepart(MM,Admission_date)

SQL Server Advanced Questions – ‘Join’ questions

61) Select FirstName, Lastname, Scholarship amount from tblStudent and tblScholarship table for all students even if they didn’t get Scolarship.

Select Firstname, Lastname, Scholarship_Amount from tblStudent A left join tblScholarship
 B on A.StudentId = B.Student_ref_id

62) Select FirstName, Lastname, Scholarship amount from tblStudent and tblScolarship table for those students who got Scolarship amount.

Select Firstname, Lastname, Scholarship_Amount from tblStudent A Inner join tblScholarship 
B on A.StudentId = B.Student_ref_id

63) Select FirstName, Lastname, Scholarship amount from tblStudent and tblScholarship table for those students who got Scolarship amount greater than 1200.

Select Firstname, Lastname, Scholarship_Amount from tblStudent A Inner join tblScholarship 
B on A.StudentId = B.Student_ref_id and Scholarship_Amount > 1200

64) Select FirstName, Lastname, Scholarship amount from tblStudent and tblScholarship table for those students who got Scolarship amount using right join.

Select Firstname, Lastname, isnull(Scholarship_Amount,0) from tblStudent A right join 
tblScholarship B on A.StudentId = B.Student_ref_id

65) Select FirstName, Lastname, Scholarship amount from tblStudent and tblScholarship table for all students even if they didn’t get Scolarship amount and set Scolarship amount as 0 for those students who didn’t get Scolarship amount.

Select Firstname, Lastname, ISNULL(Scholarship_Amount,0) from tblStudent a left join
tblScholarship B on A.StudentId = B.Student_ref_id

 Also check Top C# interview questions and answers

66) Write a query to find out the studentname who has not received any scholarship amount, and display 0 in front of his name.

Select Firstname, ISNULL(Scholarship_Amount, 0) As [Scholarship Amount]
from tblStudent A Left Outer Join [tblScholarship] B on 
A.StudentId = B.Student_ref_id where Scholarship_Amount is null

SQL Server Advanced Questions – ‘Tricky Query’

71) How to select random record form a tblstudent.

Select top 1* from tblStudent order by NEWID()

72) Write a query to create a clone of existing table without using Create Command.

Select Top 6 * INTO tblStudent_clone From tblstudent

note- ‘tblStudent_clone’ will be create in sample database

73) Write a query to calculate number of T in string ‘TECHSTUDY’.

Select LEN('TECHSTUDY') - LEN (REPLACE('TECHSTUDY', 'T', ''))

74) What will be the result of the query below?

select case when null = null then 'True' else 'False' end as Result;

Answer : False ! The reason is the proper way to compare a value in SQL server is using ‘IS’ operator and not using ‘=’.

75) What would be the output of the follwing query?

Select Case when 10 = 10 then 'Tech Study'
when 20 = 20  then 'techstudy.org'
else 'techstudy the complete debuggin solution' end as name

Answer: Tech Study

76) Write down the query to print first letter of a Name in Upper Case and all other letter in Lower Case.

Select UPPER(SUBSTRING(Firstname, 1,1))+ 
LOWER(SUBSTRING(Firstname, 2, Len(FirstName)-1))As Firstname from tblStudent

 Also check Top C# interview questions and answers

77) Write down the query to display all student name in one cell seprated by ‘,’ example:-“Sara, David, Dora, Jack, Vikram, Ross”.

Declare @name varchar(MAX) = ''
Select @name = @name + FirstName + ', ' from [tblStudent]
Select SUBSTRING(@name,1, LEN(@name)) As StudentList

SQL Server Advanced Questions – ‘SQL DDL Questions’

78) Write down the query to create tblstudent table with primary key (studentId)

Create table tblstudent(
StudnetId int identity(1,1) Not null primary key, 
Firstname varchar(50), 
LastName varchar(50), 
Admission_fee int, 
Admission_date date, 
Branch date
)

79) How to set Primary key(PK) using Alter command

Alter table tblstudent3 add primary key(StudnetId)

80) How to drop Primary key(PK) using Alter command

ALTER TABLE tblstudent
DROP CONSTRAINT PK__tblstudentid

81) Write a query to add new column in tblstudent

ALTER TABLE tblstudent
ADD Address varchar(50)

82) Write a query to drop Address column in tblstudent

ALTER TABLE tblstudent
DROP Column Address

SQL Server Advanced Questions – ‘Small Tricky SQL SERVER Queries’

85) What would be the output of following query?

    
select 15

a. 15
b. 1
c. 0
d. Could not find

Answer – A.15

86) What would be the output of following query?

select $

a. Could not find
b. 1
c. $
d. 0.00

Answer- D.0.00

87) What would be the output of following query?

select 1 + '1'

a. 11
b. 1
c. 2
d. Could not find

Answer – C.2

88) What would be the output of following query?

select '1' + 1

a. 11
b. 1
c. 2
d. Could not find

Answer – c. 2

89) What would be the output of following query?

select count('7')

a. 0
b. 1
c. 7
d. Could not find

Answer – b. 1

90) What would be the output of following query?

select count(*)

a. 0
b. 1
c. 7
d. Could not find

Answer- b. 1

91) What would be the output of following query?

select 'TechStudy' + 1

a. ‘TechStudy’
b. TechStudy
c. TechStudy1
d. Conversion failed

Answer – d. Conversion failed

92) What would be the output of following query?

select (SELECT 'TechStudy')

a. ‘TechStudy’
b. TechStudy
c. TechStudy1
d. Could not find

Answer – b. TechStudy

93) What would be the output of following query?

select 'TechStudy' + '1'

a. ‘TechStudy’
b. TechStudy
c. TechStudy1
d. Could not find

Asnwer – c. TechStudy1

94) What would be the output of following query?

select * from 'City'

a. City
b. None
c. Select all data from city table
d. Incorrect syntax

Answer – d. Incorrect syntax

95) What would be the output of following query?

select * from City, Student

a. Output will be inner join
b. Output will be only City table details
c. Output will cross join of both tables details
d. Could not find

Answer: c. Output will cross join of both tables details

96) What would be the output of following query?

select 'David' from student

a. Display David as many rows in student table
b. None
c. Display on time David
d. Could not find

Answer – a. Display David as many rows in student table

97) What would be the output of following query?

select SUM(null)

a. 0
b. None
c. NULL
d. Operand data type void type is invalid for sum operator.

Answer – d. Operand data type void type is invalid for sum operator.

98) What would be the output of following query?

select 0/9

a. 0
b. Throw error(Divide by zero error encountered.)
c. NULL
d. 1

Answer – a. 0

99) What would be the output of following query?

select 1 where null = null

a. 0
b. Nothing will return
c. NULL
d. 1

Answer – b. Nothing will return

In case you are looking for the most common Technical Interview Questions, read along:

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