Concat two columns in SELECT query - SELECT employeeid, CONCAT(firstname, lastname) AS employee_name FROM employee; Concat by adding space -> CONCAT(firstname, ' ', lastname) AS employee_name Write a query to find even records in MYSQL. SELECT * FROM EMPLOYEE WHERE id IN(SELECT id FROM EMPLOYEE WHERE id%2 = 0); Write a query to find odd records in MYSQL. SELECT * FROM EMPLOYEE WHERE id IN(SELECT id FROM EMPLOYEE WHERE id%2 <> 0); Get duplicate records from table SELECT name, count(name) FROM employee GROUP BY name HAVING(name) > 1 Get 4th Highest salary with limit function and without using limit functions SELECT name,email from users ORDER BY DESC LIMIT 4,1 Finding the highest salary select MAX(Salary) from Employee; Finding the 2nd highest salary Query-1 SELECT MAX(Salary) FROM Employee WHERE Salary NOT IN (SELECT MAX(Salary) FROM Employee); Query-2 select MAX(Salary) from Employee WHERE Salary <> (select MAX(Salary) from Employee ) Finding the nth highest