Not everyone knows how joins work but they still want to explore a wide range of data. Linked columns and relationships solve that problem. It allows data modelers to think about and define joins between data sources, and then let everyone utilize those relationships within the worksheet. The person who defines the join needs to know how the data fits together. Everyone else gets to benefit from that knowledge within a seamless UI.
When you create a Link, a linked column is automatically generated and added to the Dataset or Table. All worksheets created from the data source will have the option to add the linked column. Whether or not the linked column is added to the worksheet, users will be able to add data from the Link. They can add data from the linked column or add data from the icon on the toolbar. They will be able to explore the data that is available to add, and choose columns to add to their worksheet.
Data added in via Links is always added via a Left Join. Links only support Many-to-One or One-to-One relationships. Each row in your source object should have at most one possible result in your target object or wrong results will be introduced into worksheets that use the link.
The power of Sigma’s links is that you can do more than create links between tables. You can create a link between any two data sources in Sigma. You can create a Dataset that defines Metrics, then link it to a Table so that users can pull in additional customer information. You can create a link between two Datasets, two Tables, or any other combination.
Links allow you to create pathways of exploration, without limiting your users.
Plus, Sigma preserves the work you’ve already done to set up relationships between your database tables. Sigma Links are automatically added based on the foreign keys set in the database.
To Create a Link Between Datasets
- Use the left-hand navigation menu to navigate to the Dataset or Table you would like to create a Link for.
- Navigate to the ‘Links’ tab
- Click the ‘Edit’ button in the top right
- Click ‘Add Link to other sources’
- Use the left-hand menu to choose the data source you would like to connect to. Ensure that your source data has a one-to-one or many-to-one relationship with the target data.
- Once you select the data source, a preview will appear. Click next in the upper right when you have confirmed your selection.
- Preview your join column and the join results on the right hand side of the screen
- Click ‘Accept’ in the upper right
- You will now see your new Link listed on the Links tab
- Click Publish to save and publish your new Link