What is the purpose of a RIGHT JOIN in SQL?

A RIGHT JOIN in SQL is designed to include all the rows from the right table, while also fetching the matching rows from the left table. This means that if there are records in the right table that do not have corresponding matches in the left table, those records will still be included in the final result set. For any non-matching rows from the left table, NULL values will be displayed for the columns from the left table.

This operation is particularly useful when you want to ensure that you capture all entries from the right table, regardless of whether they have corresponding entries in the left table. The use of RIGHT JOIN is beneficial in scenarios where the right table contains critical data that must be represented in the output, even if some relationships are not present in the left table.

This understanding of RIGHT JOIN clarifies why it is not suitable to say it only includes matching rows from both tables, or excludes non-matching rows from the left table. Additionally, it does not combine all rows indiscriminately, as that would describe a full outer join, rather than the specific behavior of the RIGHT JOIN.