You can create charts which use data from multiple tables using Joins. These are inner joins and can be applied to tables within one database. Joins are useful to get trends across tables without modifying the schema of your database.
Joins can be added when creating a chart. Click on Create Chart button on Charts tab. You will be directed to the Chart creation page. To add a join for a chart, click Add filters & joins and just click on the link Add join next to the box below the label Joins.
You will immediately see a form guiding you with the details of the join. After selecting the tables & fields needed for join, click on Save button.
You will see a dropdown for the join is added to the box. It shows the field names involved in the join, with a couple of options available in the dropdown.
If you want to edit the join, you can select the Edit option from the dropdown. You will see the above form re-appear, populated with previously saved values. If you want to delete the join, you can select the Delete option from the dropdown.
You can add multiple joins, each of which appears as a dropdown in Joins box. These joins are combined using AND condition.
Please note, you cannot apply a Join between tables in different databases.