Building units and building structures are spatially related entities in the Buildings Great Britain database. Building structures are represented as polygons that show the spatial footprint of buildings. Building units are represented as points, indicating specific units or spaces within a building.
The building_unit and building_structure tables can be joined using the BLDGID field, which is present in both tables. The value of this field in the building_structure table establishes a relational link between each building unit and its corresponding building structure.
Since each building unit can belong to only one building structure, the relationship between building units and building structures is many-to-one, meaning that while many building units can be associated with a single building structure, a building unit cannot be linked to more than one structure.