[Solved] What does a FULL OUTER JOIN do in PostgreSQL? — Ans: It returns all rows from both tables, matching where possible, and NULLs where... | PostgreSQL

PostgreSQL - Joins in PostgreSQL

What does a FULL OUTER JOIN do in PostgreSQL?

AIt returns all rows from the right table and matching rows from the left table.

BIt returns only rows that have matching values in both tables.

CIt returns all rows from the left table and matching rows from the right table.

DIt returns all rows from both tables, matching where possible, and NULLs where no match exists.

Step-by-Step Solution

Solution:

Step 1: Understand the join types
INNER JOIN returns only matching rows; LEFT JOIN returns all left table rows plus matches; RIGHT JOIN returns all right table rows plus matches.
Step 2: Define FULL OUTER JOIN behavior
FULL OUTER JOIN returns all rows from both tables, matching where possible, and fills unmatched columns with NULL.
Final Answer:
It returns all rows from both tables, matching where possible, and NULLs where no match exists. -> Option D
Quick Check:
FULL OUTER JOIN = all rows both tables [OK]

Quick Trick: Remember: FULL OUTER JOIN = all rows from both tables [OK]

Common Mistakes:

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What does a FULL OUTER JOIN do in PostgreSQL?