A general-purpose programming language having language extensions for strongly typed, compile-time checked query and set operations that can be applied to arbitrary data structures, be they object-relational (O-R) mappings or just regular objects. As is appropriate for a general purpose programming language, the extensions do not mandate a particular object-relational layer; rather, they are introduced as abstractions that can be implemented in multiple environments. Accordingly, there is provided a system that facilitates data querying in accordance with an innovative aspect. The system include a program component that provides embedded query and set operations in a programming language, and an application component that facilitates application of the query and set operations over a data structure of data. The data can be any kind of data such as that found in a database, a document (e.g., XML), and data sources in a programming language (e.g., C#), for example.