Question

What is a non-equijoin?

1) An inner join that returns matching rows
2) An inner join that returns non-matching rows
3) An outer join that returns matching rows
4) An outer join that returns non-matching rows

Answer 1

A non-equijoin is an inner join that returns non-matching rows based on a specified condition. It is used to find rows that do not have matching values in the condition.

Step-by-step explanation:

A non-equijoin is an inner join that returns non-matching rows from two tables based on a specified condition.

Non-equijoins are generally used when we want to find rows that do not have matching values in the specified condition.

For example, if we have two tables - Customers and Orders - and we want to find the customers who have not placed any orders, we can use a non-equijoin on the two tables using a condition such as Customers.customer_id != Orders.customer_id.

So, option 2) An inner join that returns non-matching rows is the correct definition of a non-equijoin.