ИСТИНА

In the modern software development practice, almost every information system uses a database management system (DBMS) to store data. The most widespread database model nowadays is the relational model, which describes data as the tuples of attribute values. This model is implemented by relational database management systems. One of the aspects of data modeling in relational DBMS is the consistency constraints. Consistency constraints can be represented either as predicates over the attributes of a single tuple, or as uniqueness requirements of the subset of attributes in the whole relation, as a requirement of the existence of tuple with specified attributes in a different relation, or as a subroutine call before appending the tuple to the relation. Such subroutine call in existing relational DBMS may perform arbitrary database queries. Requests for data modification (appending or removal of a tuple or updating the attribute values) which result in a violation of consistency constraints are rejected by DBMS. The common design models for information systems interacting with DBMS are three-tier or client-server architectures. First tier (data tier) corresponds to the database. Second tier (logic tier or client) is usually implemented as an application server or a separate application written in a general purpose programming language (e.g., Java, C#, Python). Interaction with the database is implemented in the application by means of SQL language or a software library which constructs SQL queries. The application code must be consistent with the data model, which means that all possible cases of consistency constraint violation must be handled in the application. During the software lifecycle data model and constraints are usually modified to reflect the changes in requirements. Therefore, the consistency constraints handling in the application must be controlled continuously. The present paper describes the research-in-progress of the relational database model in terms of dependently-typed lambda calculus. The model can represent the consistency constraints on the relational database and statically check that application code respects the consistency constraints.