Nurql: A nested universal relation query language

摘要

The universal relation (UR) model aims to free the user from logical navigation in a relational database. A UR query language simplifies user queries since the database is queried solely through the attributes. Furthermore, the nested relational model extends the applicability of the relational model to non-business applications, and a nested relational query language provides a powerful and flexible user interface. Under the nested UR model, introduced by the authors, nested relations constitute the internal level for the nested UR scheme at the conceptual level, and a UR interface constitutes a view at the external level. Herein we describe NURQL (Nested UR Query Language), which is the query language proposed for the nested UR model, and show that NURQL combines the simplicity of a UR query language with the power of a nested relational query language.