ITSS 4301 Exam 1 Review

alternate key

In entity relationship models, a synonym for candidate key

enterprise-class database system

a DBMS product capable of supporting the operating requirements of large organizations

personal database system

a DBMS product intended for use by an individual or a small workgroup. such products typically include application development tools such as form and report generators in addition to the DBMS

primary key

a candidate key selected to be the key of a relation

ID column

a column used as a primary key that usually has surrogate key values

client-server architecture

a computer application architecture that divides the application into two parts: the client, which resides on the users' device, and the server, which resides on a centralized server computer. the server responds to requests from clients

multivalued dependency

a condition in a relation with three or more attributes in which independent attributes appear to have relationships they do not have. formally, in a relation r(a,b,c), having key (a,b,c) where a is matched with multiple values of b (or multiple of c, or both), b does not determine c and c does not determine b. as an example is the relation employee(empnumber, empskill, dependentname), where an employee can have multiple values of empskill and dependentname. empskill and dependentname do not have any relationship, but they do appear to in the relation.

concurrency

a condition in which two or more transactions are processed against the database at the same time. in a single CPU system, the changes are interleaved; in a multi-CPU system, the transactions may be processed simultaneously, and the changes on the database server are interleaved

relational model

a data model in which data are stored in relations and relationships between rows are represented by data values

Non-Relational Databases

a database constructed one a methodology other than the relational database methodology

tables

a database structure of tows and columns to create cells that hold data values. also known as a relation in a relational database, although strictly only tables that meet specific conditions can be called relations

relational database

a database that consists of relations. in practice, relational databases contain relations with duplicate rows. most DBMS products include a feature that removes duplicate rows when necessary and appropriate. such removal is not done as a matter of course because it can be time-consuming and expensive

entity class

a design for a collection of entities of the same type. typically a table or relation describes an entity class

transaction

a group of actions that is performed on the database automatically; either all actions are committed to the database or none of them are. or, in the business world, the record of an event

row

a group of columns in a table. all the columns in a row pertain to the same entity. also known as a type or a record

record

a group of fields pertaining to the same entity, used in file-processing systems. or, in the relational model, a synonym for a type or row.

key

a group of one or more attributes that identifies a unique row in a relation. because relations cannot have duplicate rows, every relation must have at least one key that is the composite of all the attributes in the relation. a key is sometimes called a logical key. with some relational DBMS products and index on a column used to improve access and sorting speed, in this case, is sometimes called a physical key

composite key

a key of a relation that consists of two or more columns

unique key

a key that identifies a unique row

nonunique key

a key that potentially identifies more than one row

structured query language (SQL)

a language for defining the structure and processing of a relational database it can be used as a stand-alone query language, or it can be embedded in application programs. SQL was developed by IBM and is accepted as a national standard by the American national standards institute.

field

a logical group of bytes in a record used with file processing. or, in the context of the relational model, a synonym for attribute

column

a logical group of bytes in a row of a relation or a table. the meaning of a column is the same for every row of the relation, and represents an attribute of a relation

fifth normal form

a normal form necessary to eliminate an anomaly where a table can be split apart but not correctly joined back together. also known as project0join normal form

entity instance

a particular occurrence of an entity

user

a person using an application

system maintenance stage

a process that starts with the implemented system as its input and produces an updated system or a request for system modification using the SDLC as its output

fourth normal form

a relation in BCNF in which every multivalued dependency is a function dependency

second normal form

a relation in first normal form in which all non-key attributes are dependent on all the attributes of a key

Boyce-codd normal form (BCNF)

a relation in third normal form in which every determinant is a candidate key

domain/key normal form (DK/NF)

a relation in which all constraint are logical consequences of domains and keys, in this text, this definition has been simplified to a relation in which the determinants of all functional dependencies are candidate keys

third normal form

a relations in second normal form that has no transitive dependencies

functional dependency

a relationship between attributes in which one attribute or group of attributes determines the value of another. the expressions x->y, "x determines y", and "y is functionally dependent on x" mean the given a value of x, we can determine a specific value of y

binary relationship

a relationship between exactly two entities or tables

ternary relationship

a relationship between three entities

referential integrity constraint

a relationship constraint on foreign key values. a referential integrity constraint specifies that the values of a foreign key must be a subset of the values of the primary key to which it refers

server

a robust computer operated by information systems staff and used to run the server portion of client server application such as web pages and email. servers are thus said to provide services to users.

child

a row, record, or node on the many side of a one-to-many relationship

database

a self-describing collection of related records or, for relational databases, of related tables

extended entity-relationship model

a set of constructs and conventions, including supertypes and subtypes, used to create data models. the things in the users' world are represented by entities, and the associations among those things are represented by relationships. the results are usually documented in an entity-relationship diagram

database management system (DBMS)

a set of programs used to define, administer, and process a database and its applications

app

a short term for application, normally applied to applications running on tablets and smartphones

modification problems

a situation that exists when the storing of one row in a table records facts about two themes or the deletion of a row removes facts about two themes, or when a data change must be made in multiple rows for consistency

virtual machine

a software emulation of a computer system

instance

a specific occurrence of an object of interest

data warehouse

a store of enterprise data that is designed to facilitate management decision making. a data warehouse includes not only data but also metadata, tools, procedures, analysis programs, training, personnel information, and other resources that make access to the data easier and more relevant to the decision makers

database development process

a subset of the systems development life cycle that specifically designs and implements the database

online analytical processing (OLAP)

a technique for analyzing data values, called measures, against characteristics associated with those data values, called dimensions

relation

a two-dimensional array that contains single-value entries and no duplicate rows. the meaning of the columns is the same in every row. the order of the rows and columns is immaterial

attribute

a value that represents a characteristic of an entity, or a column of a relation

domain integrity constraint

also called a domain constraint, a data constraint that limits data values to a particular set of values

personal computer (PC)

also known as a micro-computer; a small computer intended for use by one person as his or her own computer

modification action

an action that changes the value of a data item

database application

an application that uses a database to store the data needed by the application

relationship lass

an association between entity classes

relationship instance

an association between entity instances or a specific relationship between two tables in a database

relationship

an associations between two entities, objects, or rows of relations

candidate key

an attribute or a group of attributes that identifies a unique row in a relation,, one of the candidate keys is chosen to be the primary key

foreign key

an attribute or set of attributes that is a key of one or more relations other than the one in which it appears

null values

an attribute value that has never been supplied. such values are ambiguous and can mean the value is unknown, the value is not appropriate, or the value is known to be blank

child entity

an entity on the many side of a one-to-many relationship

composite identifier

an identifier of an entity that consists of two or more attributes

nonunique identifier

an identifier that determines a group of entity instances

unique identifier

an identifier that determines exactly one entity instance

database system

an information system composed of users, database applications, a database management system (DBMS), and a database

android operating system

an operating system (OS) developed by google and widely used on tablets and smartphones

online transaction processing (OLTP) system

an operational database system available for, and dedicated to, transaction processing

device

any equipment, such as a personal computer, that is connected to the internet

first normal form

any table that fits the definition of a relation

conceptual design, logical design, physical design

books on systems analysis and design often identify these three design stages

metadata

data concerning the structure of data in a database used to describe tables, columns, constraints, indexes, and so forth. metadata is also stored in a data warehouse to describe its contents

identifier

in an entity, a group of one or more attributes that determine entity instances

client

in client-server architecture, the software that resides on the user's computer, tablet, or smartphone

use case

in systems analysis and design, a detailed example of how a user interacts with an information system or application

implementation stage

in the systems development life cycle, the stage where hardware is acquired, software is installed, and the designed information system actually made functional for users

business intelligence (BI) systems

information systems that assist managers and other progressional in analyzing current and past activities and predicting future events. two major categories of BI systems are reporting systems and data mining systems

self-describing

inn a database, the characteristic of including data about the database in the database itself. thus, the data that define a table are included in a database long with the data that are contained in that table. these descriptive data are called metadata.

degree

inn the entity-relationship model, the number of entities participating in a relationship

information

knowledge derived from data, data presented inn a meaningful context, or data processed by summing, ordering averaging, grouping, comparing, or other similar operations

web sites

locations on the world wide web

NoSQL

not only SQL; actually referring to the creation and use of non relational DBMS products instead of just not using the SQL language, this movement was originally mislabeled the NoSQL movement. such systems may or may not use SQL-like query languages for data retrieval. it is now recognized that both relational and non relational DBMS product are needed in management information systems and that they must interact with each other. thus, the term not only SQL

determinant

one or ore attributes that functionally determine another attribute or attributes. in the functional dependency (a,b)->(d,c) the attributes (a,b) are the determinant

entity

something of importance to a user that needs to be represented in a database. in the entity relationship model, entities are restricted to things that can be represented by a single table

related tables

tables in a relationnel database that are connected by a foreign key column and a referential integrity constraint

entity integrity constraint

the constraint that the primary key column or columns must have unique values so that each row can be uniquely identified

entity-relationship model (e-r model)

the constructs and conventions used to create a model of users' data. the things in the users' world are represented by entities, and the associations among those things are represented by relationships the results are usually documented in an entity-relationship diagram

big data

the current term for the enormous datasets created by web applications, Web 2.0 social networks, scientific applications, and transaction data

systems development life cycle (SDLC)

the five stage cycle used to develop management information systems. it consists of the following stages: 1) system definition, 2) requirements analysis, 3) component design, 4) implementation, 5) system maintenance

system definition stage

the initial stage of the systems development ent life cycle (SDLC) where the project requirements and constraints are established, and the project team created

internet

the network that connects the entire Earth, and the basis for much of modern computing

database design

the process in which a general data model is translated into entities, relationships, and constraints for a specific DBMS

normalization

the process of constructing one or more relations such that in every relation the determinant of every functional dependency is a candidate key (BCNF). for 4NF, the process of removing multivalued dependencies. In general, the process of evaluating a relation to determine whether it is in a specified normal form and of connecting it to relations in that specified normal form, if necessary

domain

the set of all possible values an attribute can have, or, a description of the format and the semantics of an attribute

world wide web

the set of interconnected hypertext objects accessible on the internet, organized into web sites

web browser

the software that is used to connect to and interact with web pages

requirements analysis stage

the stage in the system development life cycle where the data model is created

component design stage

the third step in the systems development life cycle model. the system is designed based on specific hardware and software. the database design is created in this step, based on the data model created during the requirements analysis stage

cloud computing

the use of networks, such as the internet, to deliver services to users, where users are unconcerned about exactly where the servers delivering the services are located thus, the servers are said to be "in the cloud". cloud services are typically provided by large data centers owned by cloud providers

data

the values stored in database tables

web 2.0

web sites that allow users to contribute content