The page explains the SQL FULL OUTER JOIN keyword:

• A FULL OUTER JOIN returns all records when there is a match in either the left (table1) or right (table2) table. If there are rows in either table without a match in the other, those rows are still included, with NULL values for columns from the non-matching table.
• FULL OUTER JOIN is the same as FULL JOIN.
• Syntax example:

  SELECT column_name(s)
  FROM table1
  FULL OUTER JOIN table2
  ON table1.column_name = table2.column_name
  WHERE condition;
  

• Beware: This join can return very large result sets.
• Example uses sample tables "Customers" and "Orders" from the Northwind database, showing that all customers and all orders are returned, with NULL values where no matching record exists in the joined table.
• This join is useful when you want to see all data from both tables, not just the overlaps or matches.[1]

1

SQL FULL OUTER JOIN Keyword

SQL FULL OUTER JOIN Keyword

The FULL OUTER JOIN keyword returns all records when there is a match in left (table1) or right (table2) table records.

Tip: FULL OUTER JOIN and FULL JOIN are the same.

FULL OUTER JOIN Syntax

SELECT column_name(s)
FROM table1
FULL OUTER JOIN table2
ON table1.column_name = table2.column_name
WHERE condition;

Note: FULL OUTER JOIN can potentially return very large result-sets!

Demo Database

In this tutorial we will use the well-known Northwind sample database.

Below is a selection from the "Customers" table:

And a selection from the "Orders" table:

SQL FULL OUTER JOIN Example

The following SQL statement selects all customers, and all orders:

SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
FULL OUTER JOIN Orders ON Customers.CustomerID=Orders.CustomerID
ORDER BY Customers.CustomerName;

A selection from the result set may look like this:

Note: The FULL OUTER JOIN keyword returns all matching records from both tables whether the other table matches or not. So, if there are rows in "Customers" that do not have matches in "Orders", or if there are rows in "Orders" that do not have matches in "Customers", those rows will be listed as well.