Most Important SQL Query for Interview:- 1)  Write Query to add and remove a new column in tables? 2)  Write a Query to add a primary Key into a table? 3)  Write a Query to add a foreign key in a table? 4)  Write a Query to rename the table, database, and column? 5)  Write q Query to implement self join, inner join, outer join, and natural join? 6)  Write a Query to use Group by and having Most Important SQL Query for Interview:- Dept(Deptid, Deptname) Emp(Empid,Empname, Job, Salary, Deptid) 7)  WAQ to display total employee and each dept? 8)  WAQ to display the record of the employee who is getting second max salary? 9)  WAQ to select deptname and job where number of employee is more then 3? 10)  WAQ to  display max, min,avg salary on each dept excluding IT dept? 11) WAQ to display the name of dept where employee is null? 12) WAQ to display the empname whose salary is minium?