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"Unlock the power of SQL—one query at a time! 🚀"
Top 70 advanced SQL questions
and answers for query writing!

1.​ How to retrieve the second-highest salary of an employee?

SELECT MAX(salary) FROM employees​

WHERE salary < (SELECT MAX(salary) FROM employees);

2.​ How to get the nth highest salary in ?

SELECT salary​
FROM (​
SELECT salary, DENSE_RANK() OVER ​
(ORDER BY salary DESC) AS rank​
FROM employees) AS ranked_salaries WHERE rank = N;

3.​ How do you fetch all employees whose salary is greater than the
average salary?

SELECT *​
FROM employees​
WHERE salary > (SELECT AVG(salary) FROM employees);

4.​ Write a query to display the current date and time in .

SELECT CURRENT_TIMESTAMP;

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5.​ How to find duplicate records in a table?

SELECT column_name, COUNT(*) FROM table_name​

GROUP BY column_name HAVING COUNT(*) > 1;

6.​ How can you delete duplicate rows in ?

WITH CTE AS (​
SELECT column_name,​
ROW_NUMBER() OVER (PARTITION BY column_name ORDER BY​
column_name) AS row_num FROM table_name​
)​
DELETE FROM CTE WHERE row_num > 1;

7.​ How to get the common records from two tables?

SELECT *​
FROM table1 INTERSECT SELECT *​
FROM table2;

8.​ How to retrieve the last 10 records from a table?

SELECT *​
FROM employees​
ORDER BY employee_id DESC LIMIT 10;

9.​ How do you fetch the top 5 employees with the highest salaries?

SELECT *​
FROM employees ORDER BY salary DESC LIMIT 5;

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10.​ How to calculate the total salary of all employees?

SELECT SUM(salary) FROM employees;

11.​ How to write a query to find all employees who joined in the year
2020?

SELECT *​
FROM employees​
WHERE YEAR(join_date) = 2020;

12.​ Write a query to find employees whose name starts with 'A'.

SELECT * ​
FROM employees WHERE name LIKE 'A%';

13.​ How can you find the employees who do not have a manager?

SELECT *​
FROM employees​
WHERE manager_id IS NULL;

14.​ How to find the department with the highest number of employees?

SELECT department_id, COUNT(*) FROM employees​

GROUP BY department_id ORDER BY COUNT(*) DESC LIMIT 1;

15.​ How to get the count of employees in each department?

SELECT department_id, COUNT(*) FROM employees​

GROUP BY department_id;

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16.​ Write a query to fetch employees having the highest salary in each
department.

SELECT department_id, employee_id, salary​

FROM employees AS e​
WHERE salary = (SELECT MAX(salary) FROM employees​
WHERE department_id = e.department_id);

17.​ How to write a query to update the salary of all employees by 10%?

UPDATE employees​
SET salary = salary * 1.1;

18.​ How can you find employees whose salary is between 50,000 and
1,00,000?

SELECT *​
FROM employees​
WHERE salary BETWEEN 50000 AND 100000;

19.​ How to find the youngest employee in the organization?

SELECT *​
FROM employees​
ORDER BY birth_date DESC LIMIT 1;

20.​ How to fetch the first and last record from a table?

(SELECT * FROM employees ORDER BY employee_id ASC LIMIT 1)​

UNION ALL​
(SELECT * FROM employees ORDER BY employee_id DESC LIMIT 1);

21.​ Write a query to find all employees who report to a specific manager.

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SELECT *​
FROM employees WHERE manager_id = ?;

22.​ How can you find the total number of departments in the company?

SELECT COUNT(DISTINCT department_id) FROM employees;

23.​ How to find the department with the lowest average salary?

SELECT department_id, AVG(salary) FROM employees​

GROUP BY department_id ORDER BY AVG(salary) ASC LIMIT 1;

24.​ How to delete all employees from a department in one query?

DELETE FROM employees WHERE department_id = ?;

25.​ How to display all employees who have been in the company for more
than 5 years?

SELECT *​
FROM employees​
WHERE DATEDIFF(CURDATE(), join_date) > 2020;

26.​ How to find the second-largest value from a table?

SELECT MAX(column_name) FROM table_name​

WHERE column_name < (SELECT MAX(column_name) FROM table_name);

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27.​ How to write a query to remove all records from a table but keep the
table structure?

TRUNCATE TABLE table_name;

28.​ Write a query to get all employee records in XML format.

SELECT employee_id, name, department_id FROM employees​

FOR XML AUTO;

29.​ How to get the current month’s name from ?

SELECT MONTHNAME(CURDATE());
30.​ How to convert a string to lowercase in ?

SELECT LOWER('STRING_VALUE');

31.​ How to find all employees who do not have any subordinates?

SELECT *​
FROM employees​
WHERE employee_id NOT IN (SELECT manager_id FROM employees WHERE
manager_id IS NOT NULL);

32.​ Write a query to calculate the total sales per customer in a sales table.

SELECT customer_id, SUM(sales_amount) FROM sales​

GROUP BY customer_id;

33.​ How to write a query to check if a table is empty?

SELECT CASE​
WHEN EXISTS (SELECT 1 FROM table_name) THEN 'Not Empty'​
ELSE 'Empty' END;

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34.​ How to find the second highest salary for each department?

SELECT department_id, salary​

FROM (SELECT department_id, salary,​
DENSE_RANK() OVER (PARTITION BY department_id ORDER BY salary
DESC) AS rank​
FROM employees) AS ranked_salaries WHERE rank = 2;

35.​ Write a query to fetch employees whose salary is a multiple of 10,000.

SELECT *​
FROM employees​
WHERE salary % 10000 = 0;

36.​ How to fetch records where a column has null values?

SELECT *​
FROM employees​
WHERE column_name IS NULL;

37.​ How to write a query to find the total number of employees in each job
title?

SELECT job_title, COUNT(*) FROM employees​

GROUP BY job_title;

38.​ Write a query to fetch all employees whose names end with ‘n’.

SELECT *​
FROM employees WHERE name LIKE '%n';

39.​ How to find all employees who work in both departments 101 and 102?

SELECT employee_id FROM employees​

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WHERE department_id IN (101, 102) GROUP BY employee_id​
HAVING COUNT(DISTINCT department_id) = 2;

40.​ Write a query to fetch the details of employees with the same salary.

SELECT *​
FROM employees​
WHERE salary IN (SELECT salary​
FROM employees GROUP BY salary HAVING COUNT(*) > 1);

41.​ How to update salaries of employees based on their department?

UPDATE employees SET salary = CASE​

WHEN department_id = 101 THEN salary * 1.10 WHEN department_id =
102 THEN salary * 1.05 ELSE salary​
END;

42.​ How to write a query to list all employees without a department?

SELECT *​
FROM employees​
WHERE department_id IS NULL;

43.​ Write a query to find the maximum salary and minimum salary in each
department.

SELECT department_id, MAX(salary), MIN(salary) FROM employees​

GROUP BY department_id;

44.​ How to list all employees hired in the last 6 months?

SELECT *​
FROM employees​

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WHERE hire_date > ADDDATE(CURDATE(), INTERVAL -6 MONTH);

45.​ Write a query to display department-wise total and average salary.

SELECT department_id, SUM(salary) AS total_salary, AVG(salary) AS

avg_salary FROM employees​
GROUP BY department_id;

46.​ How to find employees who joined the company in the same month
and year as their manager?

SELECT e.employee_id, e.name FROM employees e​

JOIN employees m ON e.manager_id = m.employee_id WHERE
MONTH(e.join_date) = MONTH(m.join_date) AND YEAR(e.join_date) =
YEAR(m.join_date);

47.​ Write a query to count the number of employees whose names start
and end with the same letter.

SELECT COUNT(*)​
FROM employees​
WHERE LEFT(name, 1) = RIGHT(name, 1);

48.​ How to retrieve employee names and salaries in a single string?

SELECT CONCAT(name, ' earns ', salary) AS employee_info FROM

employees;

49.​ How to find employees whose salary is higher than their manager's
salary?

SELECT e.employee_id, e.name FROM employees e​

JOIN employees m ON e.manager_id = m.employee_id WHERE e.salary >
m.salary;

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50.​ Write a query to get employees who belong to departments with less
than 3 employees.

SELECT *​
FROM employees​
WHERE department_id IN (SELECT department_id FROM employees​
GROUP BY department_id HAVING COUNT(*) < 3);

51.​ How to write a query to find employees with the same first name?

SELECT *​
FROM employees​
WHERE first_name IN (SELECT first_name FROM employees​
GROUP BY first_name HAVING COUNT(*) > 1);

52.​ How to write a query to delete employees who have been in the
company for more than 15 years?

DELETE FROM employees​

WHERE DATEDIFF(CURDATE(), join_date) > 5475;

53.​ Write a query to list all employees working under the same manager.

SELECT *​
FROM employees WHERE manager_id = ?;

54.​ How to find the top 3 highest-paid employees in each department?

SELECT *​
FROM (SELECT *,​
DENSE_RANK() OVER (PARTITION BY department_id ORDER BY salary
DESC) AS rank​
FROM employees) AS ranked_employees WHERE rank <= 3;

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55.​ Write a query to list all employees with more than 5 years of
experience in each department.

SELECT *​
FROM employees​
WHERE DATEDIFF(CURDATE(), join_date) > 1825;

56.​ How to list all employees in departments that have not hired anyone in
the past 2 years?

SELECT *​
FROM employees​
WHERE department_id IN (SELECT department_id FROM employees​
GROUP BY department_id​
HAVING MAX(hire_date) < ADDDATE(CURDATE(), INTERVAL -2​
YEAR));

57.​ Write a query to find all employees who earn more than the average
salary of their department.

SELECT *​
FROM employees e​
WHERE salary > (SELECT AVG(salary) FROM employees​
WHERE department_id = e.department_id);
58.​ How to list all managers who have more than 5 subordinates?

SELECT *​
FROM employees​
WHERE employee_id IN (SELECT manager_id FROM employees​
GROUP BY manager_id HAVING COUNT(*) > 5);

59.​ Write a query to display employee names and hire dates in the format
"Name - MM/DD/YYYY".

SELECT CONCAT(name, ' - ', DATE_FORMAT(hire_date, '%m/%d/%Y')) AS

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employee_info​
FROM employees;

60.​ How to find employees whose salary is in the top 10%?

SELECT *​
FROM employees​
WHERE salary >= (SELECT PERCENTILE_CONT(0.9) WITHIN GROUP (ORDER
BY salary ASC)​
FROM employees);

61.​ Write a query to display employees grouped by their age brackets

(e.g., 20-30, 31-40, etc.).

SELECT CASE​
WHEN age BETWEEN 20 AND 30 THEN '20-30'​
WHEN age BETWEEN 31 AND 40 THEN '31-40'​
ELSE '41+'​
END AS age_bracket, COUNT(*)​
FROM employees GROUP BY age_bracket;
62.​ How to find the average salary of the top 5 highest-paid employees in
each department?

SELECT department_id, AVG(salary) FROM (SELECT department_id,

salary,​
DENSE_RANK() OVER (PARTITION BY department_id ORDER BY salary
DESC) AS rank​
FROM employees) AS ranked_employees WHERE rank <= 5​
GROUP BY department_id;

63.​ How to calculate the percentage of employees in each department?

SELECT department_id,​
(COUNT(*) * 100.0 / (SELECT COUNT(*) FROM employees)) AS
percentage FROM employees​
GROUP BY department_id;

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64.​ Write a query to find all employees whose email contains the domain
'@example.com'.

SELECT *​
FROM employees​
WHERE email LIKE '%@example.com';

65.​ How to retrieve the year-to-date sales for each customer?

SELECT customer_id, SUM(sales_amount) FROM sales​

WHERE sale_date BETWEEN '2024-01-01' AND CURDATE()​
GROUP BY customer_id;

66.​ Write a query to display the hire date and day of the week for each
employee.

SELECT name, hire_date, DAYNAME(hire_date) AS day_of_week FROM

employees;
​
67.​ How to find all employees who are older than 30 years?

SELECT *​
FROM employees​
WHERE DATEDIFF(CURDATE(), birth_date) / 365 > 30;

68.​ Write a query to display employees grouped by their salary range (e.g.,
0- 20K, 20K-50K).

SELECT CASE​
WHEN salary BETWEEN 0 AND 20000 THEN '0-20K'​
WHEN salary BETWEEN 20001 AND 50000 THEN '20K-50K' ELSE '50K+'​
END AS salary_range, COUNT(*)​
FROM employees GROUP BY salary_range;

69.​ How to list all employees who do not have a bonus?

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SELECT *​
FROM employees WHERE bonus IS NULL;

70.​ Write a query to display the highest, lowest, and average salary for
each job role.

SELECT job_role, MAX(salary) AS highest_salary, MIN(salary) AS

lowest_salary, AVG(salary) AS avg_salary​
FROM employees GROUP BY job_role;

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