When you drag into the Design Editor two or more tables that are related with each other, the relationships between these tables are shown with lines connecting the related tables. DatabaseSpy uses different colors to distinguish the individual relationships:
•Green: Self-reference, i.e. the table uses a key that is assigned to one or more of the table's own columns.
•Blue: Incoming reference, i.e. the selected table is referenced by a key used in another table.
•Orange: Outgoing reference, i.e. the table has a key defined that references one or several column(s) in another table.
Please note that the color of one and the same relation line may change depending on the table that is currently selected. For example, a foreign key relationship is displayed blue if you select the referenced table, and orange if you select the referencing table. The screenshot below shows an incoming relationship for tblAnimalCategories.
The same relationship, however viewed from the referencing tblAnimalTypes table's point of view, is depicted with an orange relation line (see screenshot below).
The screenshot below illustrates a self relation that makes sure that the manager number ("MgrNo") of an employee's manager is contained in the list of employee numbers ("EmpNo").