ids = db(db.task_run.task_scheduled ==
db.task_scheduled.id)\
(db.task_scheduled.group_name == 'status')\
(db.task_run.start_time
+status_expiration<now)._select(db.task_run.id)
db(db.task_run.id.belongs(ids)).delete()notice *_select *instead of *select*
