OUTER JOIN - LEFT

There may be times when you want to return rows from one table even if there are no matching rows.
Selects every records from the first table
This is often abbreviated and just called a left join.
For this situation we use an outer join.
With an outer join, you get all the rows that satisfy the join conditions plus all the rows from the other table.
This may leave some of the field entries blank, or "Null."
Values in the column in one table must be equal to the column in the other table (relationship uses '=' operator). It frequently involves primary and foreign key components)
A left outer join is where all the rows in the "one" table (in the "one-to-many" relationship) are returned and only matching rows from the "many" table.

You can create a left outer join by using the keywords OUTER LEFT JOIN and ON keywords
This works in both Access and SQL Server

This is an example joining the EMPLOYEES table and the SUPPLIERS table

SELECT           Employees.LastName 
                 ,Suppliers.CompanyName 
FROM             EMPLOYEES 
LEFT OUTER JOIN  SUPPLIERS 
ON               Employees.City = Suppliers.City 
WHERE            Employees.LastName IS NOT NULL 

This is an example joining the CUSTOMERS table and the ORDERS table

SELECT           Customers.CustomerID 
                 ,Customers.CompanyName 
                 ,Orders.OrderID 
FROM             CUSTOMERS 
LEFT OUTER JOIN  ORDERS 
ON               Customers.CustomerID = Orders.CustomerID 
ORDER BY         OrderID 

Also referred to as a Left Join.
A left outer join is where all the rows in the "one" table (in the "one-to-many" relationship) are returned and only matching rows from the "many" table.
The OUTER keyword is optional

This displays all Customer Names irrespective of whether they have any orders. Everything from the Customers table.

SELECT           Customers.CompanyName, 
                 Orders.OrderID 
FROM             Customers 
LEFT OUTER JOIN  Orders 
ON               Customers.CustomerID = Orders.CustomerID 
ORDER BY         OrderID 

Alternative (not supported in Access)

SELECT           Customers.CompanyName, 
                 Orders.OrderID 
FROM             Customers, 
                 Orders 
WHERE            Customers.CustomerID = Orders.CustomerID(+) 
ORDER BY         OrderID 

You can use LEFT JOIN instead of LEFT OUTER JOIN and it will have the same effect.

SELECT           Employees.LastName 
                 ,Suppliers.CompanyName 
FROM             EMPLOYEES 
LEFT JOIN        SUPPLIERS 
ON               Employees.City = Suppliers.City 
WHERE            Employees.LastName IS NOT NULL 

WHERE Alternative
This is the plus sign operator (+) and is used to do an outer join and also to see the rows that do not usually meet the join condition
This is not supported in Access

SELECT           Customers.CustomerID 
                 ,Customers.CompanyName 
                 ,Orders.OrderID 
FROM             CUSTOMERS 
                 ,ORDERS 
WHERE            Customers.CustomerID = Orders.CustomerID(+) 
ORDER BY         OrderID