An attribute can have a value according to a site.
So, the primary key of the table is the column attributeid and the column siteid.
| Name | Type | Not Null | Primary Key | Foreign Key | Remarks |
| :——— | :——— | :————- | :—————- | :—————- | :———— |
| attributeid | integer | X | X | attribute(attributeid) | This is a foreign key to the table attribute. |
| siteid | integer | X | X | site(siteid) | This is a foreign key to the table site. |
| value | bool | This is the boolean value of the attribute. |