Abstract
A multi-model approach to heterogeneous database (DB) integration requires a more user-friendly solution, i.e., a possibility to see various conceptual or data schemas in a unified way. We use a functional approach based on so-called attributes named by short natural language expressions with associated expressions describing their type.
Attributes are functions that can be manipulated by a version of typed lambda calculus, which with arithmetic and aggregation functions enables to build a powerful query language. We consider the relational, E-R, JSON, and graph data/conceptual models.
A query over such integrated DB can be expressed by a term of the typed lambda calculus. A more user-friendly version of such language can serve as a powerful query tool in practice.