An Outer Join is a type of database join (commonly used in SQL) that returns records from one or both tables even if there’s no matching record in the other table.

Types of Outer Joins:

1. LEFT OUTER JOIN (or simply: LEFT JOIN):
   → Returns all records from the left table, and the matching ones from the right table.
   → If there’s no match, the result is filled with NULL values from the right table.

2. RIGHT OUTER JOIN (or: RIGHT JOIN):
   → Returns all records from the right table, and the matching ones from the left table.
   → If there’s no match, NULL is used for the left side.

3. FULL OUTER JOIN:
   → Returns all records from both tables, with NULL where no match exists on either side.

Example:

Suppose you have two tables:

• Customers

  CustomerID	Name
  1	Anna
  2	Bernd
  3	Clara

• Orders

  OrderID	CustomerID	Product
  101	2	Book
  102	4	Lamp

LEFT JOIN (Customers LEFT JOIN Orders ON Customers.CustomerID = Orders.CustomerID)

An INNER JOIN is a term used in SQL (Structured Query Language) to combine rows from two (or more) tables based on a related column between them.

Example:

You have two tables:

Table: Customers

Table: Orders

Now you want to know which customers have placed orders. You only want the customers who exist in both tables.

SQL with INNER JOIN:

SELECT Customers.Name, Orders.Product
FROM Customers
INNER JOIN Orders ON Customers.CustomerID = Orders.CustomerID;

Result:

Explanation:

• Clara didn’t place any orders → not included.

• The order with CustomerID 4 doesn’t match any customer → also excluded.

In short:

An INNER JOIN returns only the rows with matching values in both tables.