Outer Joins
An outer join is a special join type that requires careful consideration before use. An outer join is a relationship between two tables in which records from one table do not have matching records in the other. This situation occurs frequently, particularly when your universe will access a transaction system rather than a data warehouse. For example, when a company launches a new product, sales may not yet exist for that product. So to see a report with the product listed and the sales amount displaying zero from the fact table would require an outer join.
However, it’s also possible to have items in a fact table that do not have a corresponding record in the dimension table. As an example, imagine a frustrated sales clerk who keeps ...
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