Database Query Language Research Articles

Database querying and constraint programming

The declarative programming paradigms used in constraint languages can lead to powerful extensions of relational database query languages. This is an overview of recent progress on such constraint query languages, with a list of related open theoretical computer science questions.

Concept for a Real-Time Structured Database Query Language (RT-SQL)

Real-time database management systems have become a hot topic in the research and development community of late (Fort94a, Grah93, WCPP93). In addition there has been a movement in the standards community to examine and develop extensions to existing and proposed query languages to support real-time (Fish94, Fort94, Fort94a, FS94, Gord94).This paper examines the state of research into real-time database management systems in the areas of database structuring, transaction structuring, transaction processing, concurrency control, recovery and real-time transaction scheduling. We then extend the findings and trends of this work into the high level specification of data definition language, data manipulation language and data control language extensions for the standard SQL2 and emerging SQL3 database query languages.

An enhanced construction specific SQL

The key to developing a system of information handling in construction that will have a dramatic positive impact on productivity is the development of an appropriate database language. This research involved the development of a standard construction industry specific extension to the Standard Query Language (SQL), the de facto international standard for relational database query languages. Construction Industry-SQL (CI-SOL), is the first industrial extension to SQL and serves as a prototype for a host of other extensions form other industries. CI-SQL uses object data, object attributes, and user-defined extensions to allow rapid access to industry databases. CI-SQL can play a significant role in the way information is retrieved by construction industry, allowing the development of robust databases that support SQL. Ultimately the implementation of CI-SQL will force industry to reconsider the heavy duplication of information that negatively affects productivity and will allow the introduction of keyless data entry and retrieval systems that enhance the speed and accuracy of information handling. Examples in construction material procurement will be used to illustrate the potential for CI-SQL applications. The ultimate use of CI-SQL will be to allow the use of keyless data entry systems, the foremost of which is bar coding, in construction specifications.

Comprehension syntax

The syntax of comprehensions is very close to the syntax of a number of practical database query languages and is, we believe, a better starting point than first-order logic for the development of database languages. We give an informal account of a language based on comprehension syntax that deals uniformly with a variety of collection types; it also includes pattern matching, variant types and function definition. We show, again informally, how comprehension syntax is a natural fragment of structural recursion, a much more powerful programming paradigm for collection types. We also show that a very small "abstract syntax language" can serve as a basis for the implementation and optimization of comprehension syntax.

An Environment of Generating Interactive Maps with Compromises between Users' Requirements and Limitations of Display Devices

One of the most important and novel issues of users' generating interactive maps from geographic databases is the adaptive control of the amount of visual components comprising the maps with compromises between users' requirements and limitations of display devices. If users adjust the amount by hand through database query languages, the processes must be very tedious.This paper proposes an environment of supporting users' generating maps from the point of view of new style methods of generalization for raw objects (data) retrieved from geographic databases. The environment provides automatic functions of releasing users' requirements according to limitations of display devices. Also, it aids users to decide characteristic parameters of the maps with some new concepts of measuring states of a map, such as the saturation of it, the inconsistent context of it, and ranks of visualization methods for retrieved raw objects.

A Temporal Query System for Protocol-Directed Decision Support

Chronus is a query system that supports temporal extensions to the Structured Query Language (SQL) for relational databases. Although the relational data model can store time-stamped data and can permit simple temporal-comparison operations, it does not provide either a closed or a sufficient algebra for manipulating temporal data. In this paper, we outline an algebra that maintains a consistent relational representation of temporal data and that allows the type of temporal queries needed for protocol-directed decision support. We also discuss how Chronus can translate between our temporal algebra and the relational algebra used for SQL queries. We have applied our system to the task of screening patients for clinical trials. Our results demonstrate that Chronous can express sufficiently all required temporal queries, and that the search time of such queries is similar to that of standard SQL.

Extending SQL with graph matching, set covering and partitioning

Abstract Graph matching, set covering and partitioning problems are both theoretically and practically important in decision support systems. Numerous situations have been modeled as graph matching, set covering and partitioning problems. These situations include applications in the areas of task assignment, marriage problem, airline crew scheduling, truck deliveries or vehicle routing, political redistricting, etc. Relational database systems currently support these applications merely by providing some programming languages which are used to write the programs associated with the data. These programming languages are complete as opposed to existing query languages like SQL. These languages, since they are complete, have the usual complexity of a powerful language and lack the simplicity of query languages. This increases application development effort. Relational operators and the query language SQL are extended in this present work in order to enable these problems to be stated and solved directly by the relational database systems leading to benefits of improved data independence, increased productivity, and better performance. The relational operators are extended with six operators, i.e., match, maxmatch, cover, mincover, partition, and minpartition. Properties of these operators are described. Some of these operators may possibly take a very long time in finding a solution. Genetic algorithms are proposed. These algorithms are bounded by a polynomial time. These algorithms therefore enable DBMS to be capable of responding to queries involving proposed operators in a given time constraint. The database operations and query languages extended in this research provide a powerful tool for users as a database‐query tool which supports some decision support systems for information retrieval from a database.

The EPMI Malay Basin Petroleum Geology Database: Design Philosophy and Keys to Success: ABSTRACT

Esso Production Malaysia Inc. (EPMI) developed and populated a database containing information collected in the areas of basic well data: stratigraphy, lithology, facies; pressure, temperature, column/contacts; geochemistry, shows and stains, migration, fluid properties; maturation; seal; structure. Paradox was used as the database engine and query language, with links to ZYCOR ZMAP+ for mapping and SAS for data analysis. Paradox has a query language that is simple enough for users. The ability to link to good analytical packages was deemed more important than having the capability in the package. Important elements of design philosophy were included: (1) information on data quality had to be rigorously recorded; (2) raw and interpreted data were kept separate and clearly identified; (3) correlations between rock and chronostratigraphic surfaces were recorded; and (4) queries across technical boundaries had to be seamless.

Concept for a real-time structured database query language (RT-SQL)

Real-time database management systems have become a hot topic in the research and development community of late (Fort94a,Grah93,WCPP93). In addition there has been a movement in the standards community to examine and develop extensions to existing and proposed query languages to support real-time (Fish94,Fort94,Fort94a,FS94,Gord94). This paper examines the state of research into real-time database management systems in the areas of database structuring, transaction structuring, transaction processing, concurrency control, recovery and real-time transaction scheduling. We then extend the findings and trends of this work into the high level specification of data definition language, data manipulation language and data control language extensions for the standard SQL2 and emerging SQL3 database query languages.

Spatial SQL: a query and presentation language

Recently, attention has been focused on spatial databases, which combine conventional and spatially related data, such as geographic information systems, CAD/CAM, or VLSI. A language has been developed to query such spatial databases. It recognizes the significantly different requirements of spatial data handling and overcomes the inherent problems of the application of conventional database query languages. The spatial query language has been designed as a minimal extension to the interrogative part of SQL and distinguishes from previously designed SQL extensions by: the preservation of SQL concepts; the high-level treatment of spatial objects; and the incorporation of spatial operations and relationships. It consists of two components, a query language to describe what information to retrieve and a presentation language to specify how to display query results. Users can ask standard SQL queries to retrieve nonspatial data based on nonspatial constraints, use Spatial SQL commands to inquire about situations involving spatial data, and give instructions in the Graphical Presentation Language, GPL to manipulate or examine the graphical presentation. >

A controlling scheme for Prolog through count terms

We propose an extension to Prolog called the count term for controlling Prolog execution. The purpose is to allow the programmers as well as the users to have greater flexibility in controlling the execution behavior of Prolog programs and for limiting the number of answers or proofs retrieved when Prolog is used as a database query language. Both syntax and operational semantics of the count term are defined. An implementation strategy based on WAM (Warren Abstract Machine) is provided. We analyze the possible meanings one might associate with the count term. The possible replacement of cut and fail by the count term is presented. The ease of analysis of programs with count terms is discussed.

Using SQL with object-oriented databases

We investigate how the standard database query language SQL can be extended to deal with the newly emerging trends of complex objects and object orientation. Our main concern is to extend SQL as naturally as possible, rather than to redesign SQL into “yet another” object-oriented query language. We achieve this goal through a faithful mapping from a complete object-oriented database model, compatible with recent proposals in the field, to the nested relational database model, which is widely accepted as a natural extension of the relational database model on which standard SQL is based. We provide formal definitions of syntax and semantics. We also review related research and situate our work into it.

Object-oriented query language facilitating construction of new objects

In object-oriented database systems, messages can be used to manipulate the database; however, a query language is still a required component of any kind of database system. In the paper, we describe a query language for object-oriented databases where both objects as well as behaviour defined in them are handled. Not only existing objects are manipulated; the introduction of new relationships and new objects constructed out of existing ones is also facilitated. The operations supported in the described query language subsumes those of the relational algebra aiming at a more powerful query language than the relational algebra. Among the additional operators, there is an operator that handles the application of an aggregate function on objects in an operand while still having the result possessing the characteristics of an operand. The result of a query as well as the operands are considered to have a pair of sets, a set of objects and a set of message expressions; where a message expression is a sequence of messages. A message expression handles both stored and derived values and hence provides a full computational power without having an embedded query language with impedance mismatch. Therefore the closure property is maintained by having the result of a query possessing the characteristics of an operand. Furthermore, we define a set of objects and derive a set of message expressions for every class; hence any class can be an operand. Moreover, the result of a query has the characteristics of a class and its superclass/subclass relationships with the operands are established to make it persistent.

Algebraic and calculus query languages for recursively typed complex objects

Algebraic and calculus database query languages for recursively typed complex objects based on the set and tuple constructs are studied. A fundamental characteristic of such complex objects is that, in them, sets may contain members with arbitrarily deep nesting of tuple and/or set constructs. Relative to mappings from flat relations to flat relations, the algebra without while has the expressive power of the algebra on conventional complex objects with non-recursive types. The algebra plus while has the power of the computable queries. The calculus has power equivalent to the arithmetical hierarchy and also to the calculus with countable invention for conventional complex objects. A technical tool, called “domain Turing machine,” is introduced and applied to characterize the expressive power of several classes of relational queries.

ERL: Logic for entity-relationship databases

We develop a logic for entity-relationship databases, ERL, that is a generalization of database logic. ERL provides advantages to the ER model much as FOL (first-order logic) does to the relational model: a uniform language for expressing database schema, integrity constraints, and database manipulation; clearly defined semantics; the capability to express database transformations; and deductive capabilities. We propose three query languages for ER databases called ERRC, ERSQL, and ERQBE, which are generalizations of the relational calculus, SQL, and QBE, respectively. We use example queries and updates to demonstrate the capabilities of these languages. We apply database transformations to introduce the notion of views and to show that both ERRC and ERSQL are relationally complete.

RQL: a recursive query language

Different classes of recursive queries in the relational databases are identified. It is shown that existing proposals to extend the relational query languages are either not powerful enough to express queries in many of these classes or use nonfirst normal form constructs. RQL, a recursive database query language that can be used to express recursive queries on all the classes identified, is presented. RQL is based on the relational algebra. In addition to functions that correspond to the standard and extended relational algebra operators, RQL supports functions required to express general recursive queries. The elements of RQL and the ways in which they are used to formulate complicated, but useful, recursive queries are described. The effects of the extensions embodied in RQL on the termination of recursive query evaluation are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Evaluation and optimization of query programs in an object-oriented and symbolic information system

OASIS, a database programming environment that extends UNIX with the concept of persistent objects, is discussed. The OASIS query languages extend conventional database query languages with procedural methods and general control statements. As the complexity of the languages makes it difficult to device a query optimizer based on a universally applicable algorithm, each query in OASIS is optimized based on a collection of basic patterns for which each pattern is associated with a separation query optimization algorithm. The optimization techniques for a set of basic patterns consisting of iterative statements and a set of nested statements is described. The optimization techniques discussed include an extended decomposition algorithm, evaluation of multiple conditions, data dependence analysis, and optimization of queries with arbitrary nesting. >

Example-based graphical database query languages

Several user-friendly graphical database query languages that let users formulate a query by specifying a graphically aided example on the screen are compared. One of the earliest such languages, M.M. Zloof's (1977) Query-by-Example, is described. Other languages discussed are Aggregates-by-Example, Summary-Table-by-Example, and Query-by-Statistical-Relational-Table for statistical and scientific databases; Time-by-Example for historical databases; Generalized-Query-by-Example for relational, network, and hierarchical databases; Office-by-Example, Formanager, the Natural Forms Query Language, and System-for-Business-Automation for office environments; and Picquery and Query-by-Pictorial-Example for pictorial (image) databases. The basic features, query specification and interpretation, object manipulation, query language constructs, and query processing techniques used in each of the languages are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Parametric databases

Our model, algebra and SQL-like query language for temporal databases extend naturally to parametric data, of which spatial, temporal, spatio-temporal, belief and ordinary data are special cases.

Equivalence of Datalog queries is undecidable

Datalog is a powerful query language for relational databases [10]. We consider the problems of determining containment, equivalence, and satisfiability of Datalog queries. We show that containment and equivalence are recursively unsolvable. This should be contrasted with the work of Aho, Sagiv, and Ullman on relational queries [1]. Satisfiability is easily decidable for Datalog quer ies. We also consider Datalog f which allows function symbols. Here, satisfiability is recursively unsolvable.