Equivalence of Relational Algebra and Relational Calculus Query Languages Having Aggregate Functions
نویسندگان
چکیده
منابع مشابه
Query Optimization Algorithm Based on Relational Algebra Equivalence Transformation
Query optimization is an important part of database management system. The objective of query optimization is to find an execution strategy for a distributed query which can be defined with relational algebra operations and communication primitives for transferring data between sites.This research paper suggests the heuristic approach for selecting the optimal evaluation plan and Semi-join appr...
متن کاملTeaching Relational Algebra and Relational Calculus: A Programming Approach
This paper describes how relational algebra and relational calculus can be taught using a programming approach. This is in contrast to the mathematical presentation of these topics in most database textbooks. For relational algebra, a function library implemented with Visual FoxPro allows queries to be written as a sequence of function calls--one call per relational algebra operation. For relat...
متن کاملOn Estimators for Aggregate Relational Algebra Queries
CASE-DB is a relational database management system that allows users to specify time constraints in queries. For an aggregate query AGG(E) where AGG is one of COUNT, SUM and AVERAGE, and E is a relational algebra expression, CASE-DB uses statistical estimators to approximate the query. This paper extends our earlier work on statistical estimators of CASE-DB with the following features: (a) New ...
متن کاملCS632 Notes on Relational Query Languages I
We begin with a data domain D, an (infinite) set from which all data values will be taken. Thus, while it is conventional to use distinct types for distinct fields of a data record (e.g. the SSNO field is an integer, while the NAME field is a character string), we assume the single domain D is rich enough to represent any values we might be interested in. None of the technical results below is ...
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
ژورنال
عنوان ژورنال: Journal of the ACM
سال: 1982
ISSN: 0004-5411,1557-735X
DOI: 10.1145/322326.322332