Object-Relational Mapping

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What Does Object-Relational Mapping Mean?

Object-relational mapping (ORM) is a programming technique in which a metadata descriptor is used to connect object code to a relational database. Object code is written in object-oriented programming (OOP) languages such as Java or C#. ORM converts data between type systems that are unable to coexist within relational databases and OOP languages.


Techopedia Explains Object-Relational Mapping

ORM resolves the object code and relational database mismatch with three approaches: bottom up, top-down and meet in the middle. Each approach has its share of benefits and drawbacks. When selecting the best software solution, developers must fully understand the environment and design requirements.

In addition to the data access technique, ORM’s benefits also include:

  • Simplified development because it automates object-to-table and table-to-object conversion, resulting in lower development and maintenance costs
  • Less code compared to embedded SQL and handwritten stored procedures
  • Transparent object caching in the application tier, improving system performance
  • An optimized solution making an application faster and easier to maintain

ORM’s emergence in multiple application development has created disagreement among experts. Key concerns are that ORM does not perform well and that stored procedures might be a better solution. In addition, ORM dependence may result in poorly-designed databases in certain circumstances.


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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.