Database Concepts for the Systems Analyst
Fields
- Fields are common to both files and databases.
- A field is the implementation of a data attribute.
- Fields are the smallest unit of meaningful data to be stored in a file or database.
- There are four types of fields that can be stored: primary keys, secondary keys, foreign keys, and descriptive fields.
- Primary keys are fields whose values identify one and only one record in a file.
- Secondary keys are alternate identifiers for an database.
- A single file in a database may only have one primary key, but it may have several secondary keys.