Theoretical aspects of data management include, among other areas, the foundations of query languages, computational complexity and expressive power of queries, finite model theory, database design theory, dependency theory, foundations of concurrency control and database recovery, deductive databases, temporal and spatial databases, real-time databases, managing uncertain data and probabilistic databases, and Web data.
[1] 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,[2] more powerful language based on logic programming and fixpoint logic such as Datalog were studied.
[3] The theory also explores foundations of query optimization and data integration.
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).