Glossary - Database Design and Development: An Essential Guide for IT Professionals - page 714

Primary index. An index file created with values of the primary key and corre-
sponding addresses of the rows containing the primary key values.
Primary key. A single attribute or a set of attributes that uniquely identifies an
instance of an object set or entity type and chosen as the primary key.
Procedure. Detailed steps of instructions for accomplishing a given task. In com-
puter systems, procedures are written using programming languages.
Procedural language. Language used for stating the procedure on how to obtain a
required result from a database transaction rather than just stating what result is
desired.
Process. A set of tasks to accomplish a business function. In computer systems, a
process produces outputs from inputs.
Process-driven. Design and implementation of applications where the primary
emphasis is on the business processes rather than on the data relating to busi-
ness objects.
Query. A computing function that requests data from the database, stating the para-
meters and constraints for the request.
Query optimizer. Part of the query processor in the DBMS responsible to enhance
the query for faster processing.
Query processor. A component in the DBMS that executes queries.
RAID (redundant array of inexpensive disks). A system of disk storage where data
is distributed across several drives for faster data access and improved fault
tolerance.
RDBMS. A relational database management system.
Recovery manager. Software component in the DBMS that enables database
backup and recovery from failures.
Referential integrity. Refers to two relational tables that are directly related.
Referential integrity between related tables is established if non-null values in
the foreign key attribute of the child table are primary key values in the parent
table.
Relation. In relational database systems, a relation is a two-dimensional table with
columns and rows, conforming to relational rules.
Relational algebra. A generic, procedural language containing well-defined opera-
tions for data manipulation in the relational data model.
Relational calculus. A generic, nonprocedural language for data manipulation in
the relational data model.
Relational data model. A conventional or logical data model where data is per-
ceived as two-dimensional tables with rows and columns. Each table represents
a business object; each column represents an attribute of the object; each row
represents an instance of the object.
Relational database. A database system built based on the relational data
model.
Relationship. A relationship between two objects sets or entity types represents the
associations of the instances of one object set with the instances of the other
object set. Unary, binary, or ternary relationships are the common types depend-
ing on the number of object sets participating in the relationship. A unary rela-