Microsoft Office Tutorials and References
In Depth Information
Working with Multiple Related Tables
Option 3 (right outer join): A query displaying records from both tables
displays all records from the table on the right. From the table on the
left, only records that have matching partners in the table on the right
appear.
The line that connects two tables in the Relationships view (and in Design
view as well) reflects information about how the tables are joined, as shown
in Figure 1-14. The arrow points to the table that contributes matching
records; all records from the other table display in the query datasheet.
Figure 1-14:
Join lines
and outer
joins.
When would you use an outer join? Suppose that you create a sales report
and want to see products that haven’t sold at all. You want an outer join that
shows all the products from the Products table, regardless of whether they
appear in the Order Details table.
If you create a query with fields from two tables that don’t have a
relationship defined, Access doesn’t know how to relate records, so every
combination of records between the two tables displays in the datasheet. Generally
(as you might expect), these queries won’t give you meaningful results.
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