Difference between revisions of "Entities and Attributes"
Jump to navigation
Jump to search
| Line 3: | Line 3: | ||
*Physical model: A design for an object (a car, a house, a database, etc) which includes implementation details such as size, volume, weight, etc) | *Physical model: A design for an object (a car, a house, a database, etc) which includes implementation details such as size, volume, weight, etc) | ||
** The physical reality will become the physical model | ** The physical reality will become the physical model | ||
*All many-to-many relationships must be reduced to a set of on-t--many relationships | |||
==Database Normalization== | |||
===Many people unfamiliar with database design principles often ask, “Why not just put all the data in one big table?” This single-table approach leads to problems of data redundancy (duplication) and data anomalies (data inconsistencies).=== | |||
Revision as of 17:22, 9 September 2017
- Conceptual model: A data model, usually represented by an entity relationship diagram (ERD)
- The client dream would be the conceptual model
- Physical model: A design for an object (a car, a house, a database, etc) which includes implementation details such as size, volume, weight, etc)
- The physical reality will become the physical model
- All many-to-many relationships must be reduced to a set of on-t--many relationships