Interview Questions on
SQL are based on following two tables, Employee Table and Employee Incentive
Table.
Table
Name : Employee
EMPLOYEE_ID
|
FIRST_NAME
|
LAST_NAME
|
SALARY
|
JOINING_DATE
|
DEPARTMENT
|
1
|
Jhon
|
Abraham
|
1000000
|
01-JAN-13 12.00.00 AM
|
Banking
|
2
|
Michael
|
Clarke
|
800000
|
01-JAN-13 12.00.00 AM
|
Insurance
|
3
|
Roy
|
Thomas
|
700000
|
01-FEB-13 12.00.00 AM
|
Banking
|
4
|
Tom
|
Jose
|
600000
|
01-FEB-13 12.00.00 AM
|
Insurance
|
5
|
Jerry
|
Pinto
|
650000
|
01-FEB-13 12.00.00 AM
|
Insurance
|
6
|
Philip
|
Mathew
|
750000
|
01-JAN-13 12.00.00 AM
|
Services
|
7
|
TestName1
|
123
|
650000
|
01-JAN-13 12.00.00 AM
|
Services
|
8
|
TestName2
|
Lname%
|
600000
|
01-FEB-13 12.00.00 AM
|
Insurance
|
Table Name : Incentives
EMPLOYEE_REF_ID
|
INCENTIVE_DATE
|
INCENTIVE_AMOUNT
|
1
|
01-FEB-13
|
5000
|
2
|
01-FEB-13
|
3000
|
3
|
01-FEB-13
|
4000
|
1
|
01-JAN-13
|
4500
|
2
|
01-JAN-13
|
3500
|
Database
SQL Queries Interview Questions on "SQL Select"
1.
Get all employee details from the employee table
Select * from employee
2. Get First_Name,Last_Name from employee table
Select first_name, Last_Name from employee
3. Get First_Name from employee table using alias name “Employee Name”
Select first_name Employee Name from employee
4. Get First_Name from employee table in upper case
Select upper(FIRST_NAME) from EMPLOYEE
5. Get First_Name from employee table in lower case
Select lower(FIRST_NAME) from EMPLOYEE
6. Get unique DEPARTMENT from employee table
select distinct DEPARTMENT from EMPLOYEE
7. Select first 3 characters of FIRST_NAME from EMPLOYEE
Oracle Equivalent
of SQL Server SUBSTRING is
SUBSTR, Query : select substr(FIRST_NAME,0,3) from employee
SQL
Server Equivalent of Oracle SUBSTR is SUBSTRING, Query : select
substring(FIRST_NAME,0,3) from employee
MySQL
Server Equivalent of Oracle SUBSTR is SUBSTRING. In MySQL
start position is 1, Query :select substring(FIRST_NAME,1,3) from employee
8. Get position of 'o' in name 'Jhon' from employee table
Oracle Equivalent of SQL Server CHARINDEX is
INSTR, Query : Select
instr(FIRST_NAME,'o') from employee where first_name = 'Jhon'
SQL Server Equivalent of Oracle INSTR is
CHARINDEX,Query: Select
CHARINDEX('o',FIRST_NAME,0) from employee where first_name = 'Jhon'
MySQL Server Equivalent of Oracle INSTR is
LOCATE, Query: Select
LOCATE('o',FIRST_NAME) from employee where first_name = 'Jhon'
9. Get FIRST_NAME from employee table after removing white spaces from right side
select RTRIM(FIRST_NAME) from employee
10. Get FIRST_NAME from employee table after removing white spaces from left side
select LTRIM(FIRST_NAME) from employee
11. Get length of FIRST_NAME from employee table
Oracle,MYSQL Equivalent of SQL Server Len is
Length , Query :select
length(FIRST_NAME) from employee
SQL Server Equivalent of Oracle,MYSQL Length
is Len, Query :select len(FIRST_NAME)
from employee
12. Get First_Name from employee table after replacing 'o' with '$'
select REPLACE(FIRST_NAME,'o','$') from employee
13. Get First_Name and Last_Name as single column from employee table separated by a '_'
Oracle Equivalent
of MySQL concat is '||', Query : Select FIRST_NAME||
'_' ||LAST_NAME from EMPLOYEE
SQL
Server Equivalent of MySQL concat is '+', Query : Select FIRST_NAME + '_' +LAST_NAME from
EMPLOYEE
MySQL Equivalent
of Oracle '||' is concat, Query : Select concat(FIRST_NAME,'_',LAST_NAME)
from EMPLOYEE
14. Get FIRST_NAME ,Joining year,Joining Month and Joining Date from employee table
SQL Queries in Oracle,
Select FIRST_NAME, to_char(joining_date,'YYYY') JoinYear ,
to_char(joining_date,'Mon'), to_char(joining_date,'dd') from EMPLOYEE
SQL Queries in SQL
Server, select SUBSTRING (convert(varchar,joining_date,103),7,4) , SUBSTRING
(convert(varchar,joining_date,100),1,3) , SUBSTRING
(convert(varchar,joining_date,100),5,2) from EMPLOYEE
SQL Queries in MySQL, select year(joining_date),month(joining_date),
DAY(joining_date) from EMPLOYEE
15. Get all employee details from the employee table order by First_Name Ascending
Select * from employee
order by FIRST_NAME asc
16. Get all employee details from the employee table order by First_Name descending
Select * from employee
order by FIRST_NAME desc
17. Get all employee details from the employee table order by First_Name Ascending and Salary descending
Select * from employee
order by FIRST_NAME asc,SALARY desc
Database SQL Queries
Interview Questions on "SQL Where Condition"
18. Get employee details from employee table whose employee name is “Jhon”
Select * from EMPLOYEE
where FIRST_NAME = 'Jhon'
19. Get employee details from employee table whose employee name are “Jhon” and “Roy”
Select * from EMPLOYEE
where FIRST_NAME in ('Jhon','Roy')
20. Get employee details from employee table whose employee name are not “Jhon” and “Roy”
Select * from EMPLOYEE
where FIRST_NAME not in ('Jhon','Roy')
Database SQL Queries
Interview Questions on "SQL Wild Card"
21. Get employee details from employee table whose first name starts with 'J'
Select * from EMPLOYEE
where FIRST_NAME like 'J%'
22. Get employee details from employee table whose first name contains 'o'
Select * from EMPLOYEE
where FIRST_NAME like '%o%'
23. Get employee details from employee table whose first name ends with 'n'
Select * from EMPLOYEE
where FIRST_NAME like '%n'
Database SQL Queries
Interview Questions on "SQL Pattern Matching"
24. Get employee details from employee table whose first name ends with 'n' and name contains 4 letters
Select * from EMPLOYEE
where FIRST_NAME like '___n' (Underscores)
25. Get employee details from employee table whose first name starts with 'J' and name contains 4 letters
Select * from EMPLOYEE
where FIRST_NAME like 'J___' (Underscores)
26. Get employee details from employee table whose Salary greater than 600000
Select * from EMPLOYEE
where Salary > 600000
27. Get employee details from employee table whose Salary less than 800000
Select * from EMPLOYEE
where Salary < 800000
28. Get employee details from employee table whose Salary between 500000 and 800000
Select * from EMPLOYEE
where Salary between 500000 and 800000
29. Get employee details from employee table whose name is 'Jhon' and 'Michael'
Select * from EMPLOYEE
where FIRST_NAME in ('Jhon','Michael')
30. Get employee details from employee table whose joining year is “2013”
SQL Queries in
Oracle, Select * from EMPLOYEE where to_char(joining_date,'YYYY') = '2013'
SQL Queries in
SQL Server, Select * from EMPLOYEE where
SUBSTRING(convert(varchar,joining_date,103),7,4) = '2013'
SQL Queries in
MySQL, Select * from EMPLOYEE where year(joining_date) =
'2013'
31. Get employee details from employee table whose joining month is “January”
SQL Queries in
Oracle, Select * from EMPLOYEE where to_char(joining_date,'MM') = '01' or
Select * from EMPLOYEE where to_char(joining_date,'Mon') = 'Jan'
SQL Queries in
SQL Server, Select * from EMPLOYEE where
SUBSTRING(convert(varchar,joining_date,100),1,3) = 'Jan'
SQL Queries in
MySQL, Select * from EMPLOYEE where month(joining_date) =
'01'
32. Get employee details from employee table who joined before January 1st 2013
SQL Queries in Oracle, Select * from
EMPLOYEE where JOINING_DATE < to_date('01/01/2013','dd/mm/yyyy')
SQL Queries in SQL Server (Format -
“MM/DD/YYYY”), Select * from EMPLOYEE where joining_date < '01/01/2013'
SQL Queries in MySQL (Format - “YYYY-DD-MM”), Select
* from EMPLOYEE where joining_date < '2013-01-01'
33. Get employee details from employee table who joined after January 31st
SQL Queries in Oracle, Select * from
EMPLOYEE where JOINING_DATE > to_date('31/01/2013','dd/mm/yyyy')
SQL Queries in SQL Server and MySQL
(Format - “MM/DD/YYYY”), Select * from EMPLOYEE where joining_date
>'01/31/2013'
SQL Queries in MySQL (Format - “YYYY-DD-MM”),
Select * from EMPLOYEE where joining_date >'2013-01-31'
34. Get employee details from employee table who joined between January 1st and January 31st
SQL Queries in Oracle, Select * from
EMPLOYEE where JOINING_DATE between to_date('01/01/2013','dd/mm/yyyy') and
to_date('31/01/2013','dd/mm/yyyy')
SQL Queries in SQL Server (Format -
“MM/DD/YYYY”), Select * from EMPLOYEE where joining_date between '01/01/2013'
and '01/31/2013'
SQL Queries in MySQL (Format - “YYYY-DD-MM”), Select
* from EMPLOYEE where joining_date between '2013-01-01' and '2013-01-31'
35. Get Joining Date and Time from employee table
SQL Queries in Oracle, select
to_char(JOINING_DATE,'dd/mm/yyyy hh:mi:ss') from EMPLOYEE
SQL Queries in SQL Server, Select
convert(varchar(19),joining_date,121) from EMPLOYEE
SQL Queries in MySQL, Select
CONVERT(DATE_FORMAT(joining_date,'%Y-%m-%d-%H:%i:00'),DATETIME) from EMPLOYEE
36. Get Joining Date,Time including milliseconds from employee table
SQL Queries in Oracle, select to_char(JOINING_DATE,'dd/mm/yyyy
HH:mi:ss.ff') from EMPLOYEE . Column Data Type should be “TimeStamp”
SQL Queries in SQL Server, select
convert(varchar,joining_date,121) from EMPLOYEE
SQL Queries in MySQL, Select MICROSECOND(joining_date) from
EMPLOYEE
37. Get difference between JOINING_DATE and INCENTIVE_DATE from employee and incentives table
Select
FIRST_NAME,INCENTIVE_DATE - JOINING_DATE from employee a inner join incentives
B on A.EMPLOYEE_ID = B.EMPLOYEE_REF_ID
38. Get database date
SQL Queries in Oracle, select sysdate from
dual
SQL Queries in SQL Server, select
getdate()
SQL Query in MySQL, select now()
39. Get names of employees from employee table who has '%' in Last_Name. Tip : Escape character for special characters in a query.
SQL Queries in Oracle, Select FIRST_NAME
from employee where Last_Name like '%?%%'
SQL Queries in SQL Server, Select
FIRST_NAME from employee where Last_Name like '%[%]%'
SQL Queries in MySQL,Select FIRST_NAME from employee where
Last_Name like '%\%%'
40. Get Last Name from employee table after replacing special character with white space
SQL Queries in Oracle, Select
translate(LAST_NAME,'%',' ') from employee
SQL Queries in SQL Server adn MySQL,
Select REPLACE(LAST_NAME,'%',' ') from employee
Database SQL Queries Interview Questions on
"SQL Group By Functions"
41. Get department,total salary with respect to a department from employee table.
Select
DEPARTMENT,sum(SALARY) Total_Salary from employee group by department
42. Get department,total salary with respect to a department from employee table order by total salary descending
Select
DEPARTMENT,sum(SALARY) Total_Salary from employee group by DEPARTMENT order by
Total_Salary descending
Database SQL Queries Interview Questions on
"SQL Mathematical Operations and Group By"
43. Get department,no of employees in a department,total salary with respect to a department from employee table order by total salary descending
Select
DEPARTMENT,count(FIRST_NAME),sum(SALARY) Total_Salary from employee group by
DEPARTMENT order by Total_Salary descending
44. Get department wise average salary from employee table order by salary ascending
select
DEPARTMENT,avg(SALARY) AvgSalary from employee group by DEPARTMENT order by
AvgSalary asc
45. Get department wise maximum salary from employee table order by salary ascending
select
DEPARTMENT,max(SALARY) MaxSalary from employee group by DEPARTMENT order by
MaxSalary asc
46. Get department wise minimum salary from employee table order by salary ascending
select
DEPARTMENT,min(SALARY) MinSalary from employee group by DEPARTMENT order by
MinSalary asc
47. Select no of employees joined with respect to year and month from employee table
SQL Queries in Oracle, select to_char
(JOINING_DATE,'YYYY') Join_Year,to_char (JOINING_DATE,'MM') Join_Month,count(*)
Total_Emp from employee group by to_char
(JOINING_DATE,'YYYY'),to_char(JOINING_DATE,'MM')
SQL Queries in SQL Server, select datepart
(YYYY,JOINING_DATE) Join_Year,datepart (MM,JOINING_DATE) Join_Month,count(*)
Total_Emp from employee group by datepart(YYYY,JOINING_DATE),
datepart(MM,JOINING_DATE)
SQL Queries in MySQL, select year
(JOINING_DATE) Join_Year,month (JOINING_DATE) Join_Month,count(*) Total_Emp
from employee group by year(JOINING_DATE), month(JOINING_DATE)
48. Select department,total salary with respect to a department from employee table where total salary greater than 800000 order by Total_Salary descinding
Select
DEPARTMENT,sum(SALARY) Total_Salary from employee group by DEPARTMENT having
sum(SALARY) > 800000 order by Total_Salary desc
Database SQL Queries Interview Questions on
"SQL Inner Join"
49. Select first_name, incentive amount from employee and incentives table for those employees who have incentives
Select
FIRST_NAME,INCENTIVE_AMOUNT from employee a inner join incentives B on
A.EMPLOYEE_ID = B.EMPLOYEE_REF_ID
50. Select first_name, incentive amount from employee and incentives table for those employees who have incentives and incentive amount greater than 3000
Select
FIRST_NAME,INCENTIVE_AMOUNT from employee a inner join incentives B on
A.EMPLOYEE_ID = B.EMPLOYEE_REF_ID and INCENTIVE_AMOUNT > 3000
51. Select first_name, incentive amount from employee and incentives table for all employess even if they didn't get incentives
Select
FIRST_NAME,INCENTIVE_AMOUNT from employee a left join incentives B on
A.EMPLOYEE_ID = B.EMPLOYEE_REF_ID
52. Select first_name, incentive amount from employee and incentives table for all employees even if they didn't get incentives and set incentive amount as 0 for those employees who didn't get incentives.
SQL Queries in Oracle, Select
FIRST_NAME,nvl(INCENTIVE_AMOUNT,0) from employee a left join incentives B on
A.EMPLOYEE_ID = B.EMPLOYEE_REF_ID
SQL Queries in SQL Server, Select
FIRST_NAME, ISNULL(INCENTIVE_AMOUNT,0) from employee a left join incentives B
on A.EMPLOYEE_ID = B.EMPLOYEE_REF_ID
SQL Queries in MySQL, Select FIRST_NAME,
IFNULL(INCENTIVE_AMOUNT,0) from employee a left join incentives B on
A.EMPLOYEE_ID = B.EMPLOYEE_REF_ID
53. Select first_name, incentive amount from employee and incentives table for all employees who got incentives using left join
SQL Queries in Oracle, Select
FIRST_NAME,nvl(INCENTIVE_AMOUNT,0) from employee a right join incentives B on
A.EMPLOYEE_ID = B.EMPLOYEE_REF_ID
SQL Queries in SQL Server, Select
FIRST_NAME, isnull(INCENTIVE_AMOUNT,0) from employee a right join incentives B
on A.EMPLOYEE_ID = B.EMPLOYEE_REF_ID
SQL Queries in MySQL, Select FIRST_NAME,
IFNULL(INCENTIVE_AMOUNT,0) from employee a right join incentives B on
A.EMPLOYEE_ID = B.EMPLOYEE_REF_ID
54. Select max incentive with respect to employee from employee and incentives table using sub query
SQL Queries in Oracle, select
DEPARTMENT,(select nvl(max(INCENTIVE_AMOUNT),0) from INCENTIVES where
EMPLOYEE_REF_ID = EMPLOYEE_ID) Max_incentive from EMPLOYEE
SQL Queries in SQL Server, select
DEPARTMENT,(select ISNULL(max(INCENTIVE_AMOUNT),0) from INCENTIVES where
EMPLOYEE_REF_ID = EMPLOYEE_ID) Max_incentive from EMPLOYEE
SQL Queries in SQL Server, select
DEPARTMENT,(selectIFNULL (max(INCENTIVE_AMOUNT),0) from INCENTIVES where
EMPLOYEE_REF_ID = EMPLOYEE_ID) Max_incentive from EMPLOYEE
Database SQL Queries Interview Questions on
"Top N Salary"
55. Select TOP 2 salary from employee table
SQL Queries in Oracle, select * from
(select * from employee order by SALARY desc) where rownum < 3
SQL Queries in SQL Server, select top 2 *
from employee order by salary desc
SQL Queries in MySQL, select * from
employee order by salary desc limit 2
56. Select TOP N salary from employee table
SQL Queries in Oracle, select * from
(select * from employee order by SALARY desc) where rownum < N + 1
SQL Queries in SQL Server, select top N *
from employee
SQL Queries in MySQL, select * from
employee order by salary desc limit N
57. Select 2nd Highest salary from employee table
SQL Queries in Oracle, select min(salary)
from (select * from (select * from employee order by SALARY desc) where rownum
< 3)
SQL Queries in SQL Server, select
min(SALARY) from (select top 2 * from employee) a
SQL Queries in MySQL, select min(SALARY) from (select * from
employee order by salary desc limit 2) a
58. Select Nth Highest salary from employee table
SQL Queries in Oracle, select min(salary)
from (select * from (select * from employee order by SALARY desc) where rownum
< N + 1)
SQL Queries in SQL Server, select
min(SALARY) from (select top N * from employee) a
SQL Queries in MySQL, select min(SALARY) from (select * from
employee order by salary desc limit N) a
Database SQL Queries Interview Questions on
"SQL Union"
59. Select First_Name,LAST_NAME from employee table as separate rows
select FIRST_NAME from
EMPLOYEE union select LAST_NAME from EMPLOYEE
60. Select employee details from employee table if data exists in incentive table
select * from EMPLOYEE
where exists (select * from INCENTIVES)
Database Queries Interview Questions on
"SQL Advanced Queries"
61. Select 20 % of salary from Jhon , 10% of Salary for roy and for other 15 % of salary from employee table
SELECT FIRST_NAME,
CASE FIRST_NAME WHEN 'Jhon' THEN SALARY * .2 WHEN 'Roy' THEN SALARY * .10 ELSE
SALARY * .15 END "Deduced_Amount" FROM EMPLOYEE
62. Select Banking as 'Bank Dept', Insurance as 'Insurance Dept' and Services as 'Services Dept' from employee table
SQL Queries in Oracle, SELECT distinct
DECODE (DEPARTMENT, 'Banking', 'Bank Dept', 'Insurance', 'Insurance Dept',
'Services', 'Services Dept') FROM EMPLOYEE
SQL Queries in SQL Server and MySQL,
SELECT case DEPARTMENT when 'Banking' then 'Bank Dept' when 'Insurance' then
'Insurance Dept' when 'Services' then 'Services Dept' end FROM EMPLOYEE
63. Delete employee data from employee table who got incentives in incentive table
delete from EMPLOYEE
where EMPLOYEE_ID in (select EMPLOYEE_REF_ID from INCENTIVES)
64. Insert into employee table Last Name with ''' (Single Quote - Special Character, Use single quote before special character )
Insert into employee
(LAST_NAME) values ('Test''')
65. Select Last Name from employee table which contain only numbers
Select * from EMPLOYEE
where lower(LAST_NAME) = upper(LAST_NAME)
Database SQL Queries Interview Questions on
"SQL Table Scripts"
66. Write create table syntax for employee table
Oracle -
CREATE TABLE EMPLOYEE
(
EMPLOYEE_ID NUMBER,
FIRST_NAME VARCHAR2(20
BYTE),
LAST_NAME VARCHAR2(20
BYTE),
SALARY FLOAT(126),
JOINING_DATE TIMESTAMP
(6) DEFAULT sysdate,
DEPARTMENT VARCHAR2(30
BYTE) )
SQL Server -
CREATE TABLE EMPLOYEE(
EMPLOYEE_ID int NOT
NULL,
FIRST_NAME varchar(50)
NULL,
LAST_NAME varchar(50)
NULL,
SALARY decimal(18, 0)
NULL,
JOINING_DATE
datetime2(7) default getdate(),
DEPARTMENT varchar(50)
NULL)
67. Write syntax to delete table employee
DROP table employee;
68. Write syntax to set EMPLOYEE_ID as primary key in employee table
ALTER TABLE EMPLOYEE
add CONSTRAINT EMPLOYEE_PK PRIMARY KEY(EMPLOYEE_ID)
69. Write syntax to set 2 fields(EMPLOYEE_ID,FIRST_NAME) as primary key in employee table
ALTER TABLE EMPLOYEE
add CONSTRAINT EMPLOYEE_PK PRIMARY KEY(EMPLOYEE_ID,FIRST_NAME)
70. Write syntax to drop primary key on employee table
Alter TABLE EMPLOYEE
drop CONSTRAINT EMPLOYEE_PK;
71. Write Sql Syntax to create EMPLOYEE_REF_ID in INCENTIVES table as foreign key with respect to EMPLOYEE_ID in employee table
ALTER TABLE INCENTIVES
ADD CONSTRAINT INCENTIVES_FK FOREIGN KEY (EMPLOYEE_REF_ID) REFERENCES
EMPLOYEE(EMPLOYEE_ID)
72. Write SQL to drop foreign key on employee table
ALTER TABLE INCENTIVES
drop CONSTRAINT INCENTIVES_FK;
73. Write SQL to create Orcale Sequence
CREATE SEQUENCE
EMPLOYEE_ID_SEQ
START WITH 0
NOMAXVALUE MINVALUE 0 NOCYCLE NOCACHE NOORDER;
74. Write Sql syntax to create Oracle Trigger before insert of each row in employee table
CREATE OR REPLACE
TRIGGER EMPLOYEE_ROW_ID_TRIGGER
BEFORE INSERT ON
EMPLOYEE FOR EACH ROW
DECLARE
seq_no number(12);
BEGIN
select
EMPLOYEE_ID_SEQ.nextval into seq_no from dual ;
:new EMPLOYEE_ID :=
seq_no;
END;
SHOW ERRORS;
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