Question

Poonam has written a query in Mysql to display the details of all employees from EMP table, who do not have any value in the salary field. Select * from Emp where Salary <> NULL; Help Poonam to run the query by removing the errors from the query and rewriting it.​

Answer 1

Answer:

In simple terms, NULL is simply a place holder for data that does not exist. When performing insert operations on tables, they will be times when some field values will not be available.

In simple terms, NULL is simply a place holder for data that does not exist. When performing insert operations on tables, they will be times when some field values will not be available.In order to meet the requirements of true relational database management systems, MySQL uses NULL as the place holder for the values that have not been submitted. The screenshot below shows how NULL values look in database.

hope it helps you:)