A join in the model indicates a relationship between one fact table and one dimension table.
A join in the model indicates a relationship between one fact table and one dimension table. When you use the Add to Model wizard to model data, the wizard creates joins automatically between a fact table and each of its corresponding dimension tables.
When you model fact and dimension tables individually, joins are automatically created between them if the join references exist in the source tables.
You can also manually create joins in the data model. To do this, you drag and drop a dimension table to a fact table, or click Create Join in the Joins area.
When you define a join between a fact table and dimension table, you select a join column from each table. You can create a join on more than one column.
Join Fact and Dimension Tables
Define joins between fact tables and dimension tables to enable querying of related data. For example, you can define a join between the Profit Metrics fact table and the Products dimension table.
- In Data Modeler, lock the model for editing.
- In the Dimensions Tables area, drag and drop a dimension table to the Fact Tables area. Or, in the Joins area, click Create Join.
- In the Joins area, specify the appropriate Fact Table, Fact Column, Dimension Table, and Dimension Column to use for the join.
For example, you might specify a billing date column and a calendar date column.
- Click the checkmark icon to save the changes to the join.
If you want to remove your changes, then click the X icon. If you start to create a new join and click X, then the new row for the join is removed from the Joins table.
After you create joins, you can see the default hierarchies and levels when you click the Hierarchies tab for the given dimension table.