This illustration shows the database schema for the Charts application. Every table has a system-defined Id field. The Region table has two user-defined fields, Name and Population. The Sales table has three user-defined fields, Year, Region, and Sales. The Summary table has three user-defined fields: Region, Year, and Sales. At the bottom of each business object is the accessor name for the referenced business object, if there is one. A Region can have any number of Sales and any number of Summary objects. A Sales object can have zero or one Region; a Summary object can also have zero or one Region.