Types of Joined Views

When you join two views together, the first view is known as the left view and the second view as the right view. The three main types of joined views are as follows:

Type	Meaning	Example
One-to-one	Each record in the left view corresponds to one record in the right view	1994 Sales by Region and 1995 Sales by Region
Many-to-one	Several records in the left view refer to the same record in the right view	Customer and Sales Reps; or Counties and States
One-to-many	Each record in the left view has several matching records in the right view	Sales Reps and Customers; or States and Counties

In a one-to-many join, there are two options for the handling of right records:

Option	Meaning
Normal	The right records are left as is, and the values for each left record are repeated for each matching right record. The resulting view has one record for each right view record that has a corresponding record in the left view.
Aggregate	The right records are combined and summary measures (sum, average, low value, high value, count) are generated and displayed along with each record in the left view. The resulting view has one record for each left record.

The inner join option lets you create a joined view that includes only those left records that have a corresponding record in the right view. Without this option (by default), a joined view contains all the records from the left view. The near match option lets you create a joined view where value of the joined field does not match exactly. This option is very useful for creating lookup tables. Finally, SelfAggregate() lets you create views that are aggregate representations of an existing view, where records are grouped together based on the value of a single field.