Editing Database theory

{{Short description|Study of database design and use}}
{{more footnotes|date=November 2015}}
'''Database theory''' encapsulates a broad range of topics related to the study and research of the theoretical realm of [[database]]s and [[database management  system]]s.

Theoretical aspects of data management include, among other areas, the foundations of query languages, [[Computational complexity theory|computational complexity]] and [[expressive power (computer science)|expressive power]] of queries, [[finite model theory]], [[database design]] theory, [[dependency theory (database theory)|dependency theory]], foundations of [[concurrency control]] and [[database recovery]], [[deductive database]]s, [[temporal database|temporal]] and [[spatial database]]s, [[real-time database]]s, managing [[uncertain data]] and [[probabilistic database]]s, and Web data.

Most research work has traditionally been based on the [[relational model]], since this model is usually considered the simplest and most foundational model of interest. Corresponding results for other data models, such as object-oriented or [[semi-structured model]]s, or, more recently, graph data models and [[XML]], are often derivable from those for the relational model.<ref>{{cite web|title=A website on the Theoretical Foundations of Data Management |url=http://databasetheory.org/|language=en}}</ref>

Database theory helps one to understand the complexity and power of query languages and their connection to [[logic]]. Starting from [[relational algebra]] and [[first-order logic]] (which are equivalent by [[Codd's theorem]]) and the insight that important queries such as [[graph reachability]] are not expressible in this language,<ref>Aho, A.V. and Ullman, J.D., 1979, January. Universality of data retrieval languages. In Proceedings of the 6th ACM SIGACT-SIGPLAN symposium on Principles of programming languages (pp. 110-119).</ref> more powerful language based on [[logic programming]] and [[fixpoint logic]] such as [[Datalog]] were studied.<ref>Maier, D., Tekle, K.T., Kifer, M. and Warren, D.S., 2018. Datalog: concepts, history, and outlook. In Declarative Logic Programming: Theory, Systems, and Applications (pp. 3-100).</ref> The theory also explores foundations of [[query optimization]] and [[data integration]]. Here most work studied [[conjunctive query|conjunctive queries]], which admit query optimization even under constraints using the [[chase (algorithm)|chase]] algorithm.

The main research conferences in the area are the [[ACM Symposium on Principles of Database Systems]] (PODS) and the [[International Conference on Database Theory]] (ICDT).

==See also==
{{main category|Database theory}}
*[[Data integration]]
*[[Conjunctive query]]
*[[Expressive power (computer science)|Expressive power]]

==References==
{{Reflist}}

===General references===
* {{Citation
|last=Abiteboul
|first=Serge
|author-link=Serge Abiteboul
|last2=Hull
|first2=Richard B.
|author2-link=Richard B. Hull
|last3=Vianu
|first3=Victor
|author3-link=Victor Vianu
|title=Foundations of Databases
|publisher=Addison-Wesley
|year=1995
|isbn=0-201-53771-0
|url=https://archive.org/details/foundationsofdat0000abit
|url-access=registration
}}
* [[David Maier]], The Theory of Relational Databases. Copyright 1983 David Maier. Available at http://web.cecs.pdx.edu/~maier/TheoryBook/TRD.html

==External links==
*{{Commons category-inline}}

{{Database}}

[[Category:Database theory| ]]
[[Category:Database management systems|Theory]]