Full join return rows when there are matching rows in any one of the tables. This means it returns all the rows from the left-hand side table and all the rows from the right-hand side table.

In SQL, there is no specific “FULL JOIN” keyword. However, you can achieve a full join using a combination of LEFT JOIN, RIGHT JOIN, and UNION clauses. A full join combines the results of both LEFT JOIN and RIGHT JOIN, including unmatched rows from both tables.

Here’s an example using the following two tables:

Table A: employees

employee_id | employee_name

------------|---------------

1           | Alice

2           | Bob

3           | Charlie

Table B: departments

department_id | department_name

--------------|-----------------

1             | Sales

4             | Marketing

A full join of these two tables would include all rows from both tables, filling in NULL values for columns where there are no matches. The SQL query for a full join would be:

SELECT *

FROM employees

FULL JOIN departments ON employees.employee_id = departments.department_id;

The result would look something like this:

employee_id | employee_name | department_id | department_name

------------|---------------|---------------|-----------------

1           | Alice         | 1             | Sales

2           | Bob           | NULL          | NULL

3           | Charlie       | NULL          | NULL

NULL        | NULL          | 4             | Marketing

In this example, all rows from both tables are included, and NULL values are filled in where there are no matches. Note that the syntax for a full join may vary slightly depending on the specific database system you are using.