Database Design
The Database Schema
- Transforming the logical data model into a physical relational database schema rules and guidelines: (continued)
- The following technical details must usually be specified for each attribute.
- Data type. Each DBMS supports different data types, and terms for those data types.
- Size of the Field. Different DBMSs express precision of real numbers differently.
- NULL or NOT NULL. Must the field have a value before the record can be committed to storage?
- Domains. Many DBMSs can automatically edit data to ensure that fields contain legal data.
- Default. Many DBMSs allow a default value to be automatically set in the event that a user or programmer submits a record without a value.