ISA245 exam 1

operational database

deal with day to day operations (transactions, inventory, payrolll)

analytical database

forecasting, looking at trends

database management system

specialized piece of software that allows for creation and access to a database

database application

application software to support a business process using a database and DBMS

file-based system

an application program designed to manipulate data files

data redundancy

files and applications are created by different departments and fields need updated in more than one table

data isolation

a property that determines when and how changes made by an operation become visible to other concurrent users and systems

integrity problems

refers to the maintenance and assurance that the data in a database are correct and consistent

security problems

there are constraints regarding accessing privileges

concurrency

the ability of the database to allow multiple users access to the same record without adversely affecting transaction processing

database management software

powerful software tool that allows you to store, manipulate, and retrieve data in a variety of different ways

data

factual information such as measurements or statistics about objects and ceoncepts

data element

single fact

data inconsistency

various copies of the same data are conflicting

database approach

allows the management of large amounts of organizational information

fixed format text files

fields without headers, aligned by field

flat file

any file not part of a database

database

shared collection of related data used to support the activities of a particular organization

self describing

not only contains the database itself, but also metadata

metadata

defines and describes the data and relationships between tables in the database

program data independence

the insulation between the programs and data

view

a subset of a database, defined and dedicated for particular users of the system

concurrency control strategies

features of a database that allow several users access to the same data item at the same time

database constraint

a restriction or rule that dictates what can be entered or edited in a table

data type

determines the sort of data permitted in a field

data uniqueness

ensures that no duplicates are entered

read only access

ability to read a file but not make changes

read and write privileges

ability to read and modify a file

data independence

the system data descriptions or data describing data are separated from the application programs

entity

represents real world object such as employee

attributes

represent properties such as employee name and address

relationship

represents an association among entities

relational model

represents data as relations (tables)

instance

a record within a table

network model

represents data as record types

set type

a limited type of one to many relationship

hierarchical model

represents data as a hierarchical tree structure. each branch represents a number of related records

data modeling

conceptual design, describes data contained in DB, relationships, and constraints

database logical design

defines a database in a data model of a specific DBMS

database physical design

defines the internal database storage structure, file organization, or indexing techniques

data model

a collection of concepts or notations for describing data, data relationships, data semantics, and data constraints

operating system

provide concepts that describe the bdetails of how data are stored in computer’s memory

schemas

overall descriptions of a database

entity relationship diagram

a data model describing the database showing tables, attributes, and relationships

data independence

the immunity of user applications to changes made in the definition and organization of data

logical schema

a conceptual design of the database done on paper

external schema

user view

logical data independence

the ability to change the logical schema without changing the external schema

physical data independence

the immunity of the internal model to changes in the physical model

conceptual data models

concern the real world organization of data

logical data models

concern the efficient organization of the data for storage and retrieval

traditional models

data models that preceded the relational model

object oriented data models

a database management system in which information is represented in the form of objects as used in object oriented programming

centralized database system

the DBMS and database are stored at a single site that is used by several other systems too

distributed database system

the actual database and the DBMS software are distributed from various sites that are connected by a computer network

many

foreign key goes on the ___ side of a one to many

homogenous distributed database system

use the same DBMS software at multiple sites

heterogenous distributed database systems

different sites might use different DBMS software, but there is additional common software to support data exchange between sites

relation

(table or file) a subset of the cartesian product of a list of domains characterized by a name; the technical term for table or file

tuple

technical term for row or record

principle storage units

columns/fields/attributes

domain

the original sets of atomic values used to model data; a set of acceptable values that a column is allowed to contain

atomic value

each value in the domain is invisible as far as the relational model is concerned

records

contain fields that are related, such as customer or an employee

degree

the number of attributes in a table

entity relationship data model

(ER schema) well suited to data modeling for use with databases because it is fairly abstract and easy to discuss and explain

entity

an object in the real world with an independent existence that can be differentiated from other objects

existence dependent

cannot exist without a relationship with another entity

entity type

defines a collection of similar entities

entity set

a collection of entities of an entity type at a particular point in time

independent entity

(kernels) building blocks of a database; what other tables are built on

dependent entities

(derived entities) depend on other tables for their meaning

characteristic entity

provide more information about another table

simple attributes

those drawn from the atomic value domains

composite attributes

those that consist of a hierarchy of attributes

multivalued attributes

attributes that have a set of values for each entity

derived attributes

contain values calculated from other attributes

stored attribute

physically saved to database

key

an attribute or a group of attributes whose values can be used to uniquely identify an individual entity in an entity set

candidate key

a simple or composite key that is unique and minimal

composite key

composed of two or more attributes, must be minimal

primary key

a candidate key that is selected by the database designer to be used an an identifying mechanism for the whole entity set

secondary key

an attribute used strictly for retrieval purposes

alternate key

all candidate keys not chosen as primary

foreign key

an attribute in a table that references the primary key in another table or it can be null

unary relationship

a relationship exists between occurrences of the same entity set

ternary relationship

a relationship type that involves many to many relationships between three tables

constraint

the rules that force DBMS to check that data satisfies the semantics

domain integrity

restricts the values of attributes in the relation and is a constraint of the relational model

integrity constraints

logical statements that state what data values are or are not allowed and which format is suitable for an attribute

entity integrity

requires that every table have a primary key; neither the primary key, nor any part of it can contain null values

referential integrity

requires that a foreign key must have a matching primary key or it must be null

orphan record

one whose foreign key value is not in the corresponding entity - where primary key is located

enterprise constraints

(semantic constraints) additional rules specified by users or database administrators and can be based on multiple tables

business rules

obtained from users when gathering requirements and are used to determine cardinality

cardinality

describes the relationship between two data tables by expressing the minimum and maximum number of entity occurrences associated with one occurrence of a related entity

connectivity

the relationship between two tables (many to one)

relationship type

the type of relationship between two tables in an ERD

identifying relationship

where the primary key contains the foreign key

non-identifying relationship

does not contain the foreign key in the primary key