Entity-Relationship Diagrams
A database's contents are not very useful without determining the relationships (connections) between pieces of data so that both input and output can be made. One way to create a database is to begin with drawing an Entity-Relationship diagram. Eventually, your database will be made of of tables, reports, queries, and forms, all of which rely on relationships.
The ERD below is just a start of a doctor' office database. Entities are named with single nouns. The crow's foot shows that one patient can have zero to many procedures. PatientID and ProcedureID are logical primry keys (PKs). ProcedureID placed in Patient serves as the foreign key (FK) to connect these two entities. You can guess that once this diagram would be complete, DoctorID is likely a primary key in another entity. Lastly, note the consistent use of Pascal case and no spaces in attribute names.
The relationships in the image below show a simplified college class registration as it might look in a Microsoft Access database.
Learn more about reading ERDs here.
© 2008- Tamara Fudge