Top 23 SQL Interview Questions & Answers

https://youtu.be/l_dph6Qu4LA

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https://t.me/etl_sql_interview/8

Answer:

1. Select FIRST_NAME AS WORKER_NAME from Worker;

2. Select upper(FIRST_NAME) from Worker;

3. Select distinct DEPARTMENT from Worker;

4. Select substring(FIRST_NAME,1,3) from Worker;

5.Select INSTR(FIRST_NAME, BINARY'a') from Worker where FIRST_NAME = 'Amitabh';

6.Select RTRIM(FIRST_NAME) from Worker;

7.Select LTRIM(DEPARTMENT) from Worker;

8.Select distinct length(DEPARTMENT) from Worker;

9.Select REPLACE(FIRST_NAME,'a','A') from Worker;

10.Select CONCAT(FIRST_NAME, ' ', LAST_NAME) AS 'COMPLETE_NAME' from Worker;

11.Select * from Worker order by FIRST_NAME asc;

12.Select * from Worker order by FIRST_NAME asc,DEPARTMENT desc;

13.Select * from Worker where FIRST_NAME in ('Vipul','Satish');

14.Select * from Worker where FIRST_NAME not in ('Vipul','Satish');

15. Select * from Worker where DEPARTMENT like 'Admin%';

16. Select * from Worker where FIRST_NAME like '%a%';

17. Select * from Worker where FIRST_NAME like '%i';

18. Select * from Worker where FIRST_NAME like '_h';

19. Select * from Worker where SALARY between 100000 and 500000;

20.Select * from Worker where year(JOINING_DATE) = 2014 and month(JOINING_DATE) = 2;

21. SELECT COUNT(*) FROM worker WHERE DEPARTMENT = 'Admin';

22. SELECT CONCAT(FIRST_NAME, ' ', LAST_NAME) As Worker_Name, Salary
FROM worker
WHERE WORKER_ID IN
(SELECT WORKER_ID FROM worker
WHERE Salary BETWEEN 50000 AND 100000);

23. SELECT DEPARTMENT, count(WORKER_ID) No_Of_Workers
FROM worker
GROUP BY DEPARTMENT
ORDER BY No_Of_Workers DESC;

24. SELECT DISTINCT W.FIRST_NAME, T.WORKER_TITLE
FROM Worker W
INNER JOIN Title T
ON W.WORKER_ID = T.WORKER_REF_ID
AND T.WORKER_TITLE in ('Manager');

25. SELECT WORKER_TITLE, AFFECTED_FROM, COUNT(*)
FROM Title
GROUP BY WORKER_TITLE, AFFECTED_FROM
HAVING COUNT(*) > 1;

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Q-21. Write an SQL query to fetch the count of employees working in the department ‘Admin’.

Q-22. Write an SQL query to fetch worker names with salaries >= 50000 and <= 100000.

Q-23. Write an SQL query to fetch the no. of workers for each department in the descending order.

Q-24. Write an SQL query to print details of the Workers who are also Managers.

Q-25. Write an SQL query to fetch duplicate records having matching data in some fields of a table.

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https://t.me/etl_sql_interview/32

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Q-26. Write an SQL query to show only odd rows from a table.

Q-27. Write an SQL query to show only even rows from a table.

Q-28. Write an SQL query to clone a new table from another table.

Q-29. Write an SQL query to fetch intersecting records of two tables.

Q-30. Write an SQL query to show records from one table that another table does not have.

Click below links

To Refer three tables for writing queries👇
https://t.me/etl_sql_interview/8

To Refer questions for writing queries👇
https://t.me/etl_sql_interview/34

Answers:

26. SELECT * FROM Worker WHERE MOD (WORKER_ID, 2) <> 0;

27. SELECT * FROM Worker WHERE MOD (WORKER_ID, 2) = 0;

28. SELECT * INTO WorkerClone FROM Worker;

29. (SELECT * FROM Worker)
INTERSECT
(SELECT * FROM WorkerClone);

30. SELECT * FROM Worker
MINUS
SELECT * FROM Title;

covers many interesting interview questions checkout This playlist 👇


https://youtube.com/playlist?list=PLdrw9_aIADIPAMJW8I_S-S747oyiRtzpS


Tip: Try to do just one per day
( If possible two/day on weekends )

Click below link to Refer three tables here for writing queries 👇

https://t.me/etl_sql_interview/8

Q-31. Write an SQL query to show the current date and time.

Q-32. Write an SQL query to show the top n (say 10) records of a table.

Q-33. Write an SQL query to determine the nth (say n=5) highest salary from a table.

Q-34. Write an SQL query to determine the 5th highest salary without using TOP or limit method.

Q-35. Write an SQL query to fetch the list of employees with the same salary.

To Refer three tables for writing queries👇
https://t.me/etl_sql_interview/8

To Refer questions for writing queries👇
https://t.me/etl_sql_interview/37

Answers :

31. SELECT SYSDATE FROM DUAL;

32. SELECT * FROM (SELECT * FROM Worker ORDER BY Salary DESC)
WHERE ROWNUM <= 10;

33. SELECT Salary FROM Worker ORDER BY Salary DESC LIMIT n-1,1;

34. SELECT Salary
FROM Worker W1
WHERE 4 = (
SELECT COUNT( DISTINCT ( W2.Salary ) )
FROM Worker W2
WHERE W2.Salary >= W1.Salary
);

35. Select distinct W.WORKER_ID, W.FIRST_NAME, W.Salary
from Worker W, Worker W1
where W.Salary = W1.Salary
and W.WORKER_ID != W1.WORKER_ID;

Most commonly asked SQL interview questions

https://youtu.be/L-URbfgxBMQ

Click below link to Refer three tables here for writing queries 👇

https://t.me/etl_sql_interview/8

Q-36. Write an SQL query to show the second highest salary from a table.

Q-37. Write an SQL query to show one row twice in results from a table.

Q-38. Write an SQL query to fetch intersecting records of two tables.

Q-39. Write an SQL query to fetch the first 50% records from a table.

Q-40. Write an SQL query to fetch the departments that have less than five people in it.

To Refer three tables for writing queries👇
https://t.me/etl_sql_interview/8

To Refer questions for writing queries👇
https://t.me/etl_sql_interview/41

Answers :

36. Select max(Salary) from Worker
where Salary not in (Select max(Salary) from Worker);

37. select FIRST_NAME, DEPARTMENT from worker W where W.DEPARTMENT='HR'
union all
select FIRST_NAME, DEPARTMENT from Worker W1 where W1.DEPARTMENT='HR';

38. (SELECT * FROM Worker)
INTERSECT
(SELECT * FROM WorkerClone);

39.SELECT *
FROM WORKER
WHERE WORKER_ID <= (SELECT count(WORKER_ID)/2 from Worker);

40. SELECT DEPARTMENT, COUNT(WORKER_ID) as 'Number of Workers' FROM Worker GROUP BY DEPARTMENT HAVING COUNT(WORKER_ID) < 5;

Click below link to Refer three tables here for writing queries 👇

https://t.me/etl_sql_interview/8

Q-41. Write an SQL query to show all departments along with the number of people in there.

Q-42. Write an SQL query to show the last record from a table.

Q-43. Write an SQL query to fetch the first row of a table.

Q-44. Write an SQL query to fetch the last five records from a table.

Q-45. Write an SQL query to print the name of employees having the highest salary in each department.

To Refer three tables for writing queries👇
https://t.me/etl_sql_interview/8

To Refer questions for writing queries👇
https://t.me/etl_sql_interview/43


Answers :

41. SELECT DEPARTMENT, COUNT(DEPARTMENT) as 'Number of Workers' FROM Worker GROUP BY DEPARTMENT;

42. Select * from Worker where WORKER_ID = (SELECT max(WORKER_ID) from Worker);

43. Select * from Worker where WORKER_ID = (SELECT min(WORKER_ID) from Worker);

44. SELECT * FROM Worker WHERE WORKER_ID <=5
UNION
SELECT * FROM (SELECT * FROM Worker W order by W.WORKER_ID DESC) AS W1 WHERE W1.WORKER_ID <=5;

45. SELECT t.DEPARTMENT,t.FIRST_NAME,t.Salary from(SELECT max(Salary) as TotalSalary,DEPARTMENT from Worker group by DEPARTMENT) as TempNew
Inner Join Worker t on TempNew.DEPARTMENT=t.DEPARTMENT
and TempNew.TotalSalary=t.Salary;

SQL Interview Questions

Basic Level : https://intellipaat.com/blog/interview-question/sql-interview-questions/#11


Intermediate Level :

https://intellipaat.com/blog/interview-question/sql-interview-questions/#12


Advance Level :

https://intellipaat.com/blog/interview-question/sql-interview-questions/#13

Commonly asked questions - yet many of us fell short to clearly explain in interview

Difference between concepts which looks similar but they aren't ( eg: where vs having, Exists vs In.. etc )

Part 1 :
https://youtu.be/RZc4QSRRk98

Part 2 :
https://youtu.be/s1QkS4PfiFg