9.3 : Glossary

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This is a glossary of words, phrases, abbreviations and acronyms used in relational database design or in this chapter, which may not be familiar to the reader. Terms are ordered conceptually rather than alphabetically.

  • Tcl "Tool Control Language," a flexible interpreter designed primarily by John Ousterhout at UC Berkeley. Extensible and powerful, it is a viable competitor of the perl language. Tk is the X11 toolkit extension to Tcl.
  • WWW World Wide Web, common usage for the "web" of sites running HTTP (hyper text transfer protocol) servers offering HTML (hyper text markup language) documents across IP connections.
  • app short for "application", an application program
  • freeware common parlance for software which is made available free of charge by its author(s)
  • file-system, filesystem the structure of files on a disk medium which is visible via the operating system, i.e. the structure of files which a Unix user can see using "ls" and other tools
  • inload database managers' term for the process of loading data from "flat files" on disk into an online database
  • Database Literally, any collection of data; in this context, a related collection of tables of data
  • Relational Describes the design of tables of data such that key fields within each table relate it to other tables
  • Table A collection of information which has been organized into multiple rows, each row consisting of a fixed number of columns, each column being consistent in semantics and type across the entire table; also an Entity or Class
  • Field A column of a table of data, also called an Attribute
  • Record A row of a table, also called an Instance of a Class
  • Schema The design for a relational database, including the complete definition of tables and the relationships between them
  • RDBMS Relational Database Management System, a software package which manages a relational database, optimized for rapid and flexible retrieval of data; also called a database engine
  • Server A host on which an RDBMS capable of accepting IP connections is running; a host which can answer SQL queries across a network. Also the server process which is running on that host.
  • Backend another name for the server process or "back end" of the database, the front end being the user interface
  • SQL Structured Query Language, an ANSI standard language designed for manipulation of relational databases; some superset of ANSI SQL is built into every RDBMS
  • Oracle A major commercial RDBMS
  • Sybase Another major commercial RDBMS
  • Ingres Another major commercial RDBMS
  • Postgres95 A major non-commercial RDBMS, descendant of Ingres
  • Query A SQL statement resulting in the return of data from an RDBMS
  • Entity In relational algebra, a meaningful unit of information in the real world which should be modelled as a table; something which has attributes
  • EER diagram Entity-Entity Relationship Diagram, a specialized schematic diagram used by relational DB designers to document a schema
  • One-to-many A possible relation between tables in a schema, in which one entity can be associated with multiple instances of another entity (one Customer, for example, can have many Invoices); this is sometimes called a parent-child relationship, by analogy with tree structures.
  • Primary key Every table should have one field (attribute) which is unique to each record, or at least some combination of fields which taken together are unique to each record. There is no other way to distinguish a single record reliably. This field or combination is called the primary key.
  • Foreign key A field in a table which links it to another related table (Customer ID might link a customer with the customer's invoice). More accurately, if field X is the primary key of table A and also appears in table B, it is a foreign key in table B.
  • Index To facilitate rapid retrieval of data, all RDBMS provide some facility for building indices on tables. Different indices can be built for each field, or an index can be built on some combination of fields. The sort algorithms used for the index will almost always be variants on B-tree and heap sort.
  • Access control all RDBMS provide some mechanism for internal access control; each connecting process has a "user id" and not all user id's are able to see all tables or all fields of a given table. Privileges are similar to file protection bits in a file system but more elaborate: read, write, update, delete are the basic set, and there are many more in some RDBMS.
  • Cartesian Cross-Product Ill-formed queries can result in the generation of enormous return data sets which are the cartesian cross product of two or more large tables. This type of query can exhaust the resources of the server.
  • RSE Record Selection Expression, that part of a SQL query which determines which records will be returned
  • FSE Field Selection Expression, that part of a SQL query which determines which fields will be returned

    De Clarke
    UCO/Lick Observatory
    University of California