| A | B |
|---|
| Data design | Fields records, files, and keys and how to built these elements into a data management system |
| Entity | Is a person, place, thing, or event for which data is collected and maintained |
| Field | Single characteristic or fact about the enitity |
| Record | Is a collection of fields that describes one instance of an entity |
| File | Is a set of records that contains data about a specific entity |
| Key Field | Used to locate, retrieve, or identify a specific record |
| Primary Key | Field or combo of fields that uniquely and minimaly identitfies a particular member of an entity |
| Candidate Key | Any field that could serve as a primary key |
| Foreign Key | A field in one file that must match the primary key value in another file to establish a relationship |
| Referential Identity | Ensures that a foreign key value cannot be entered unless it matches an existing primary key |
| Secondary Key | A field or combo of fields that can be used to access or retreive records |
| Relationship | A logical link between entitys based on how they interact |
| Entity Relationship Diagram | Graphical model of an information system that show the realtionship among system entities |
| One to One Relationship | Exists when exactly one of the second entity occurs for each instance of the first entity |
| One to Many Raltionship | Exists when one occurance of the first entity can be related to many occurances of the second |
