Final answer:
Option 4: FULL OUTER JOIN is the correct answer because it uniquely retains all tuples from both sides of the join whether there is a matching tuple or not, and fills in NULLs where no matches are found.
Step-by-step explanation:
The statement given describes a FULL OUTER JOIN, which is a concept in database management, specifically in SQL (Structured Query Language). A FULL OUTER JOIN is used to combine rows from two or more tables based on a related column between them. This type of join will keep all tuples from both tables, including those that do not have a matching tuple in the other table. The question is requesting to identify the type of JOIN operation that matches the description.
To answer the question directly, Option 4: FULL OUTER JOIN is the correct option because it is the only type of join that preserves all the tuples from both sides of the join regardless of whether there is a join partner or not.
As a result, if there is no matching row between the two tables being joined, the result set will still contain all rows from both tables, with NULL values in the columns from the table that lacks a matching row. This is different from an INNER JOIN (Option 1), which only returns rows with matching values in both tables. A LEFT OUTER JOIN (Option 2) retains all rows from the left table but only matching rows from the right table, while a RIGHT OUTER JOIN (Option 3) does the opposite.