Add and Define Logical Joins

You use the Logical Diagram to add and define joins between logical tables.

When you drag multiple tables from the physical layer to the logical layer, corresponding logical tables and logical columns are created, and a logical join is automatically created for each physical join. You can modify these joins as needed, or add new joins.

See About Logical Joins.

Note:

Use caution when specifying a driving table. Driving tables are used for query optimization only under rare circumstances and when the driving table is small (fewer than 1000 rows). Choosing a driving table incorrectly can lead to severe performance degradation. See What Are Driving Tables?

1. On your home page, click Navigator and then click Semantic Models.
2. In the Semantic Models page, click a semantic model to open it.
3. Click a table, right click, and select Show Logical Diagram and select Selected Tables Only.
4. Drag and drop additional tables to the Logical Diagram.
5. Working in the Logical Diagram, hover over the first table in the join (the table representing many in the one-to-many join.), grab its handle, and drag to the table that you want to join to (the table representing one in the one-to-many join).
   A box is displayed around the table that you are joining to.
6. In Add Join, modify the values in the Cardinality, Driving Table, and Join Type fields as needed.
7. Click Add.