DWS Interview Question: What does ORM mean? What are ... | Glassdoor

Interview Question

One Out of: Java and .NET (Developer) Or Solution Architect (Not Decided) Interview Melbourne (Australia)

What does ORM mean? What are the advantages of using an

  ORM? What are some commercially available ORMs?
sql, database, db, object-oriented, orm, object-relational impedance mismatch

Interview Answer

1 Answer


Object-Relational Mapping.

Advantages: Lets the devloper deal with objects in the business domain instead of database tables (relations). Manages connection and possibly transactions. Some ORMs can abstract from the relational model and span several different data sources, including files or XML, or connect to different DB servers, abstracting from the particular query language used. If working with an IDE, having the relational model as an object model can provide syntax help (like Visual Studio's IntelliSense).

Unfortunately, I have seen in several projects how at the end of the project, when deployment is on its way and real-world performance becomes an issue, that developers start to circumvent the ORM and write native SQL. Recently I heard the opinion "ORMs considered harmful", so I'm not a totally convinced proponent of ORMs.

Example ORMs (from the .Net world): nHibernate, LinQ to SQL, Entity Framework. And of course everything here: http://en.wikipedia.org/wiki/List_of_object-relational_mapping_software

Interview Candidate on Oct 8, 2012

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