Editing Data modeling (section)

=== Data models ===
{{main|Data model}}
[[File:3-4 Data model roles.svg|thumb|320px|How data models deliver benefit.<ref name="MW99"/>]]
Data models provide a framework for [[data]] to be used within [[information system]]s by providing specific definitions and formats. If a data model is used consistently across systems then compatibility of data can be achieved. If the same data structures are used to store and access data then different applications can share data seamlessly. The results of this are indicated in the diagram. However, systems and interfaces are often expensive to build, operate, and maintain. They may also constrain the business rather than support it. This may occur when the quality of the data models implemented in systems and interfaces is poor.<ref name="MW99">Matthew West and Julian Fowler (1999). [https://sites.google.com/site/drmatthewwest/publications/princ03.pdf Developing High Quality Data Models] {{Webarchive|url=https://web.archive.org/web/20200909121755/https://d2024367-a-62cb3a1a-s-sites.googlegroups.com/site/drmatthewwest/publications/princ03.pdf?attachauth=ANoY7crjITgBSUdEyb3UlEOS2OxXk3r-iJk0-S4EfbK3PtqCZvEgcZwvpBiF3VGC7M0IMhTWLZoERz8Otd2Tu5Bquzo4NmuOxyeAzvQa0DZlSIea0KlbnoKFHPK9zM3Pg1p7f2b_OcaIv3_J8mkFK8rMoR_UABqsAM_Pa9wd6qHK1by_hBvYNRPKQZpTM4-rqh1D4x68mcRDzADCED8sFixAn4Nezq0zd_hunEOcJ8m7FSTyRa2xnOA%3D&attredirects=0 |date=September 9, 2020 }}. The European Process Industries STEP Technical Liaison Executive (EPISTLE).</ref>

Some common problems found in data models are:
* Business rules, specific to how things are done in a particular place, are often fixed in the structure of a data model. This means that small changes in the way business is conducted lead to large changes in computer systems and interfaces. So, business rules need to be implemented in a flexible way that does not result in complicated dependencies, rather the data model should be flexible enough so that changes in the business can be implemented within the data model in a relatively quick and efficient way.
* Entity types are often not identified, or are identified incorrectly.  This can lead to replication of data, data structure and functionality, together with the attendant costs of that duplication in development and maintenance. Therefore, data definitions should be made as explicit and easy to understand as possible to minimize misinterpretation and duplication.
* Data models for different systems are arbitrarily different. The result of this is that complex interfaces are required between systems that share data. These interfaces can account for between 25 and 70% of the cost of current systems. Required interfaces should be considered inherently while designing a data model, as a data model on its own would not be usable without interfaces within different systems.
* Data cannot be shared electronically with customers and suppliers, because the structure and meaning of data have not been standardised. To obtain optimal value from an implemented data model, it is very important to define standards that will ensure that data models will both meet business needs and be consistent.<ref name="MW99"/>