The term SQL stands for Structured Query Language,it’s a programming language that’s used to update and communicate with the database. SQL skills are indispensable and are in demand as with the boost in technology, data is piling up. And, In today’s world this data has become a necessity for every organization. In this post there are a lot of SQL Queries with answers which are likely to be asked during an interview.
Consider the below table for reference while trying to solve the questions asked.
Employee Details
Ques-1 Write an SQL Query to fetch the EmpId and FullName of all the
employees working under Manager with ID- 321.
Ans- We can use EmployeeDetails to fetch the data from the MangerId.
SELECT EmpId,
FullName
FROM
EmployeeDetails
WHERE ManagerId = 321;
Ques-2 Write an SQL Query to fetch common details from the two
tables.
Ans- INTERSECT operator is used in SQL to fetch the common details.
SELECT
* FROM EmployeeSalary
INTERSECT
SELECT * FROM ManagerSalary;
In the case of MySQL, we use the sub-query as
MySQL does not have the INTERSECT operator.
SELECT
*
FROM
EmployeeSalary
WHERE
EmpId IN
(SELECT EmpId from ManagerSalary);
Ques-3 Write an SQL query to find current date and time.
Ans-
Finding
date and time in MySQL
SELECT
NOW();
Finding date and time in SQL Server
SELECT getdate();
Finding date and time in Oracle
SELECT SYSDATE FROM DUAL;
Ques-4 Write an SQL Query to update the employee name by removing leading and
trailing spaces.
Ans- The functions LTRIM and RTRIM can be used with the update command to
remove the space characters.
UPDATE
EmployeeDetails
SET
FullName = LTRIM(RTRIM(FullName));
Ques-5 Write the SQL Query to fetch the first record from table
EmployeeDetails.
Ans- The query to fetch the first record is
SELECT *
FROM EmployeeDetails
WHERE
Rownum = 1;
Ques-6 Write a query to find all
the employees whose salary is between 10,000 to 12,000.
Ans- The query to find the salary of the employees ranging between 10,000
to 12,000 is-
SELECT
* FROM EmployeeSalary
WHERE
Salary BETWEEN ‘10000’ AND ‘12000’;
Ques-7 Write an SQL query to fetch all the employees working on Project other
than P1.
Ans- We can use NOT operator to find the rows which are not satisfying the
condition mentioned above
SELECT
EmpId
FROM
EmployeeSalary
WHERE NOT Project=’P1′;
Or, we can also use NOT Equal to operator
SELECT
EmpId
FROM
EmployeeSalary
WHERE
Project <> ‘P1’;
Ques-8 Write an SQL query to fetch records that are present in one table but
not in another table.
Ans- This can be done with the help of MINUS operator, which is used to
subtract the result obtained via the first query from the result obtained by
the second query.
SELECT
* FROM EmployeeSalary
MINUS
SELECT
* FROM ManagerSalary;
For MySQL we can use left join as MySQL does
not have the MINUS operator.
SELECT
EmployeeSalary.*
FROM
EmployeeSalary
LEFT
JOIN
ManagerSalary
USING (EmpId)
WHERE
ManagerSalary.EmpId IS NULL;
Ques-9 Write an SQL query to fetch the position of a given character(s) in a
field.
Ans- INSTR function is used to return the location of a substring inside a
string.
SELECT
INSTR(FullName, ‘Snow’)
FROM EmployeeDetails;
Ques-10 Write an SQL query to upper case the name of the employee and lower
case the city values.
Ans- With the help of SQL Upper and Lower function the desired result can be
accomplished.
SELECT
UPPER(FullName), LOWER(City)
So, this is the end of the article. We have covered some of the important questions that are asked during the SQL Queries interview and the ways in which you can excel yourself before any interview. Thanks for reading.:-)
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