The Join operations are used to combine tables together - either laterally or vertically. Joins and Unions can be added to the data flow to add them to the database schema. Joins can also be added and edited from Data Model, which is the semantic layer of logic that is used to describe the structure of the data model. Joins defined in this semantic layer are not added to the database schema; rather, they are used only in the querying process.

There are many circumstances in which you may want to add joins. Merge joins are useful when joining new machine learning tables to the original source table, for instance. Or you may want to join a new Summarize or Date Range table to its source table.

Alternatively, you may have tables in the data source that you want joined in a single table in the new data model, to make navigation and querying easier for end users.

Join Operations

  • Join: add a join between 2 tables, combining columns from each table and adding the join to the database schema.
  • Union: create a union between 2 or more tables, combining rows from each table and adding the union to the database schema.

Previewing Joins

By default, the preview panel displays 50 rows, which may not be enough to preview joins. Use the Preview Size drop-down in the ribbon to show more rows in the preview panel.