A schedule trigger fires when a report job is scheduled to run. Schedule triggers are of type SQL Query.
When a report job is scheduled to run, the schedule trigger executes the SQL statement defined for the trigger. If data is returned, then the report job is submitted. If data is not returned from the trigger SQL query, the report job is skipped.
The schedule trigger that you associate with a report job can reside in any data model in the catalog. You do not need to create the schedule trigger in the data model of the report for which you which to execute it. You can reuse schedule triggers across multiple report jobs.