Two-Dimensional Specification of Universal Quantification in a Graphical Database Query Language
نویسندگان
چکیده
We propose a technique for specifying universal quantification and existential quantification (combined with negation) in a two-dimensional (graphical) database query language. Unlike other approaches that provide set operators to simulate universal quantification, this technique allows a direct representation of universal quantification. We present syntactic constructs for specifying universal and existential quantifications, two-dimensional translation of universal quantification to existential quantification (with negation), and translation of existentially quantified two-dimensional queries to relational queries. The resulting relational queries can be processed directly by many existing database systems. Traditionally, universal quantification has been considered a difficult concept for typical database programmers. We claim that this technique renders universal quantification easy to understand. To substantiate this claim, we provide a simple, easy-to-follow guideline for constructing universally quantified queries. We believe that the direct representation of universal quantification in a two-dimensional language is new and that our technique contributes significantly to the understanding of universal quantification in the context of database query languages.
منابع مشابه
انتخاب مناسبترین زبان پرسوجو برای استفاده از فراپیوندها جهت استخراج دادهها در حالت دیتالوگ در سامانه پایگاه داده استنتاجی DES
Deductive Database systems are designed based on a logical data model. Data (as opposed to Relational Databases Management System (RDBMS) in which data stored in tables) are saved as facts in a Deductive Database system. Datalog Educational System (DES) is a Deductive Database system that Datalog mode is the default mode in this system. It can extract data to use outer joins with three query la...
متن کاملGRAQULA: A Graphical Query Language for Entity-Relationship or Relational Databases
GRAQULA is a graphical language for querying and updating a database. One version of GRAQULA provides a user interface for the entity-relationship data model, and another version (with almost identical syntax) provides a user interface for the relational model. Each version is relationally complete, and each depicts relationships (or expected joins) graphically. GRAQULA provides logical operati...
متن کاملPlayful Query Specification with DataPlay
DataPlay is a query tool that encourages a trial-and-error approach to query specification. DataPlay uses a graphical query language to make a particularly challenging query specification task quantification easier. It constrains the relational data model to enable the presentation of nonanswers, in addition to answers, to aid query interpretation. Two novel features of DataPlay are suggesting ...
متن کاملA Logical Framework for the Specification of Transactions (Extended Version)
In this paper a logical framework called ULTRA is presented that can serve as the basis for a variety of update languages, among others extensions of the database language SQL, accommodating nested update queries and universal quantification over updates. We give a complete definition of the syntax and semantics of the ULTRA language based on concepts of logic databases. A natural candidate for...
متن کاملSet Comparison in Relational Query Languages
Today’s de facto database standard, the relational database, was conceived in the late 1960’s by Edgar F. Codd at IBM. The relational data model offered the user a logical view of the data that was shielded from consideration of how the data would, in fact, be physically organized in storage. This feat was accomplished in large part by the introduction of relational query languages that would s...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- IEEE Trans. Software Eng.
دوره 18 شماره
صفحات -
تاریخ انتشار 1992