Object-oriented querying of existing relational databases

In this paper, we present algorithms which allow an object-oriented querying of existing relational databases. Our goal is to provide an improved query interface for relational systems with better query facilities than SQL. This seems to be very important since, in real world applications, relational systems are most commonly used and their dominance will remain in the near future. To overcome the drawbacks of relational systems, especially the poor query facilities of SQL, we propose a schema transformation and a query translation algorithm. The schema transformation algorithm uses additional semantic information to enhance the relational schema and transform it into a corresponding object-oriented schema. If the additional semantic information can be deducted from an underlying entity-relationship design schema, the schema transformation may be done fully automatically. To query the created object-oriented schema, we use the Structured Object Query Language (SOQL) which provides declarative query facilities on objects. SOQL queries using the created object-oriented schema are much shorter, easier to write and understand and more intuitive than corresponding S Q L queries leading to an enhanced usability and an improved querying of the database. The query translation algorithm automatically translates SOQL queries into equivalent SQL queries for the original relational schema

Query Translation Supporting the Migration of Legacy Databases into Cooperative Information Systems

In this paper, we present a query translation algorithm which allows object-oriented queries to be automatically translated into a relational query language. Our goal is to provide a unique and powerful query interface supporting the cooperation of information systems, particularly under the aspect of migrating existing systems without changes into the cooperation. Translation algorithms, like the one proposed in this paper are essential parts of CISs to mediate between the common global query language and the query languages of participating components. Our query translation algorithm ensures a fully automatic translation of object-oriented queries into equivalent SQL queries for the original relational schema in all cases where a direct translation is possible. In all other cases, it generates SQL queries providing a superset of the desired data and a sequence of formatting functions that transform the data into the desired result

Integration of Relational Databases in a Multidatabase System based on Schema Enrichment

In this paper, we describe a framework for an object-oriented modeling of meta information and its use for the integration of heterogeneous databases with the goal of their interoperation. The meta information consists of all types of information necessary to access and interoperate the participating databases. As part of the meta information, we model the common properties and differences of the various data models and concrete systems. Additionally, we also include information to semantically enhance the schemas of the participating databases providing the basis for a (semi-)automatic schema transformation. We describe the semantic enrichment of a relational schema using additional information deduced from its underlying entity-relationship design schema. The enhanced relational schemas may be automatically transformed into corresponding schemas in the common data model which in our case is the object-oriented model. Queries using the created objectoriented schema may be automatically translated into equivalent SQL queries for the original relational schema

Query Translation . . . into a Relational Query Language

In this paper, we present a query translation algorithm which allows object -oriented queries to be automatically translated into a relational query language. Our goal is to provide an improved query interface for existing relational database systems. The translation algorithm, we propose in this paper may be used to directly access relational databases, but it may also be useful in the context of object-oriented multidatabase systems to translate the common global query language into the query languages of participating relational databases. Necessary steps in providing object-oriented access to relational databases are schema enrichment and transformation as well as query translation. The main focus of this paper is the query translation which has to be performed fully automatically since it has to be done each time, a query is processed by the system, whereas schema enrichment and transformation may be done only once in the beginning. Our query translation algorithm ensures a full automatic translation of object-oriented queries into equivalent SQL queries for the original relational schema in all cases where a direct translation is possible. In all other cases, it generates SQL queries providing a superset of the desired data and a sequence of `formatting' functions that transform the data into the desired result. Problems may occur if additional user defined functions are used

Integration of Relational Databases in a

In this paper, we describe a framework for an object-oriented modeling of meta information and its use for the integration of heterogeneous databases with the goal of their interoperation. The meta information consists of all types of information necessary to access and interoperate the participating databases. As part of the meta information, we model the common properties and differences of the various data models and concrete systems. Additionally, we also include information to semantically enhance the schemas of the participating databases providing the basis for a (semi-)automatic schema transformation. We describe the semantic enrichment of a relational schema using additional information deduced from its underlying entity-relationship design schema. The enhanced relational schemas may be automatically transformed into corresponding schemas in the common data model which in our case is the object-oriented model. Queries using the created objectoriented schema may be automatically translated into equivalent SQL queries for the original relational schema

for Semantic Schema Enrichment

In this paper, we describe a framework for an object-oriented modeling of meta information. The meta information consists of all kind of information necessary to access and interoperate the participating databases. As part of the meta information, we model the common properties and differences of the various data models and concrete systems. We also include information to semantically enhance the schemas of the participating databases and provide the basis for an automatization of the schema transformation process. We describe possibilities to (semi-)automatically transform flat relational schemas into structured object-oriented ones which are more adequate to model complex real world problems. We use the object-oriented data model as target model of the transformation because of its semantic richness and its availability as commercial systems. The meta information necessary for the schema transformation may be user supplied or it may be deduced from an entity -relationship design schema and corresponding mapping information

Towards a Logic-Based Reconstruction of Software Configuration Management

this paper, configuration management is presented from a logic perspective. It is shown that much functionality can be generated automatically when configurations are considered as views on a deductive database and recent results on deductive integrity checking, query optimization, and intensional updates are applied. 1 The Problem Version and configuration management has been a major focus of research in practically all areas of computer-aided design, especially those like software engineering in which the whole design and production process happens within the system. Most research has been invested in the efficient production and reproduction of software components, e.g., in order to avoid excessive re-compilation efforts when only a small portion of a large system has changed. Complementary to this aspect is the consistent (re-)construction of a configuration, i.e., a construction process that satisfies a large set of different kinds