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Chapter 3. Working with Multiple-Table Queries > Creating Other Types of Joins

Creating Other Types of Joins

So far you've worked only with inner joins, which is as it should be because inner joins are by far the most common, particularly in a business environment. However, the three other types of joins—outer, self, and theta—can also come in handy and are discussed in the next three sections.

Creating Outer Joins

An outer join is one where all the records in one table are included in the dynaset regardless of whether there are matching records in the other table. For example, suppose you're dealing with Northwind's Customers and Orders tables, which are related on the common CustomerID field. An inner join between these tables shows only those customers who have placed orders. By contrast, an outer join on the Customers table displays all the records from that table, even customers who have never placed an order.


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