Editing Object–relational mapping (section)

==Challenges==
A variety of difficulties arise when considering how to match an object system to a relational database. These difficulties are referred to as the [[object–relational impedance mismatch]].<ref>[https://www.semanticscholar.org/paper/Object-Relational-Mapping-Revisited-A-Quantitative-Lorenz-Rudolph/708ac5e798b7e45b949d42e2f872549a3612e1e2 Object–Relational Mapping Revisited - A Quantitative Study on the Impact of Database Technology on O/R Mapping Strategies. M Lorenz, JP Rudolph, G Hesse, M Uflacker, H Plattner. Hawaii International Conference on System Sciences (HICSS), 4877-4886] (DOI:10.24251/hicss.2017.592)</ref>

An alternative to implementing ORM is use of the native procedural languages provided with every major database. These can be called from the client using SQL statements. The [[Data access object|Data Access Object]] (DAO) design pattern is used to abstract these statements and offer a lightweight object-oriented interface to the rest of the application.<ref>{{cite web |last=Feuerstein |first=Steven |author2=Bill Pribyl |date=September 1997 |title=Oracle PL/SQL Programming |url=http://docstore.mik.ua/orelly/oracle/prog2/ch18_05.htm |access-date=23 August 2011 |language=en-US |location=18.5 Modifying Persistent Objects}}</ref>

ORMs are limited to their predefined functionality, which may not cover all edge cases or database features. They usually mitigate this limitation by providing users with an interface to write raw queries, such as Django ORM.<ref>{{Cite web |title=Performing raw SQL queries {{!}} Django documentation |url=https://docs.djangoproject.com/en/5.1/topics/db/sql/ |access-date=2024-09-08 |website=Django Project |language=en}}</ref>