In a nutshell, a join is an SQL operation performed to establish a connection between two (or more) database tables based on matching columns, thereby creating a relationship between the tables.

Types of joins

• Cross join. A cross join returns all possible combinations of rows of two tables (also called a Cartesian product).

• Join/inner join. An inner join, also known as a simple join, returns rows from joined tables that have matching rows.

• Left outer join/left join.

• Right outer join/right join.

• Full outer join.