Definitions
- Relational database: A collection of tables.
- Table: A collection of columns (attributes) describing an entity. Individual objects are stored as rows of data in the table.
- Property (attribute): a characteristic or descriptor of a class or entity.
- Every table has a primary key.
- The smallest set of columns that uniquely identifies any row
- Primary keys can span more than one column (concatenated keys)
- We often create a primary key to insure uniqueness (e.g., CustomerID, Product#, . . .) called a surrogate key.
EmployeeID TaxpayerID LastName FirstName HomePhone Address
12512 888-22-5552 Cartom Abdul (603) 323-9893 252 South Street
15293 222-55-3737 Venetiaan Roland (804) 888-6667 937 Paramaribo Lane
22343 293-87-4343 Johnson John (703) 222-9384 234 Main Street
29387 837-36-2933 Stenheim Susan (410) 330-9837 8934 W. Maple