1. Enable Lightning Joined Reports (Beta) : To start working with joined reports in Lightning Experience, opt your Salesforce org into the beta.
2. How Joined Reports Work : A joined report can contain data from multiple standard or custom report types. You can add report types to a joined report if they have relationships with the same object or objects. For example, if you have a joined report that contains the Opportunities report type, you can add the Cases report type as well because both have a relationship with the Accounts object.
3. Add a Report Type to a Joined Report . Adding a report type lets you expand the set of data available for analysis in a joined report.
4. Change the Principal Report Type: The principal report type controls how common fields are named. A joined report must have a principal report type. You can change the principal report type at any time
5. Custom Summary Formulas with Joined Reports :Two types of custom summary formulas are available with joined reports: standard and cross-block.
6. Work with BlocksBlocks let you create different views of the information contained in a joined report.
7. Joined Report ExamplesCreating a sales rep performance scorecard, reviewing support cases by status, and predicting your opportunity pipeline are some examples of what you can do with joined reports. Here’s how.
8. Joined Report Limits, Limitations, and AllocationsMost of the things you can do with summary or matrix reports you can also do with joined reports, such as find, add, and remove fields; summarize fields; and run and save reports. However, there are some things you can’t do. When working with Lightning Experience joined reports, there are some Lightning Experience-specific limits and limitations to consider.