Can you explain how a FULL JOIN works in SQL?

FULL JOIN (or FULL OUTER JOIN) in SQL combines rows from two tables, returning all records from both tables. If there is no match for a row from one table in the other, the resulting set will have NULL values for the missing columns.

Example:

SELECT * FROM tableA
FULL JOIN tableB ON tableA.id = tableB.id;

This will return all rows from tableA and tableB, joined by the condition, and if there are no matches, the corresponding fields will be NULL.

FULL JOIN is useful when you need to get a complete dataset from both tables, including unmatched records.