INFORMATION TECHNOLOGY 2 Flashcards
Bit
Binary digit 0 or 1
Smallest storage unit in a computer
Byte
group of bits - usually 8 bits
treated as a single unit or character
Field
group of related chartacters
Record
set of related fields
File
group of records arranged in sequence
Table
group of records in a relational database with unique identifier in each record
Array
aggregate that consists of data objects with attributes , each uniquely referenced by an index or address
esample of array:
employee name, id #, ss #
Master file
file containing relatively permanent information and periodically updated with a detail transaction file
Detail Transaction file
file containing current transaction information used to update the master file
Traditional file processing systems
focus upon data processing needs of individual departments
Each application or program developed to meet the individual needs of the department
Advantages of traditional processing system
available and operational in most systems
cost effective if using simple applications
Disadvantages of traditional processing system
data files dependent upon a particular program
duplication of data between files
expensive maintenance
each application developed individually
data difficult to share between functional areas
DATA FILE STRUCTURE
Traditional processing
Database systems
What is a database system?
computer hardware and software
that enables the database to be implemented
What is a database?
collection of interrelated files stored online or offline
What is normalization in database?
Separating the database into logical tables
to avoid updating difficulties(anomalies)
Database management system?
software
that facilitates communications
between application programs and database
Data independence?
concept that separates data
from related application programs
Data modeling?
identifying and organizing data
logically and physically
determines what info sb contained in the database
how info will be used
how items in database will be related to each other
Entry relationship modeling? or
Entity relationship diagram? ERD
a data modeling
divides the database into 2 logical parts:
entities
relations
Primary key in data modeling in relational database?
Field that makes a record in a relational database table unique
Foreign key in data modeling of relational database?
Fields common to two or more related tables in a relational database
REA data model?
Resources -
Events
Agents - people from which data is collected
designed for accounting information database
Data dictionary/ data depository/ data directory?
data structure
that stores meta data
Meta data?
definitional data
provides information/documentation
of other data managed within an application
Structured query language? SQL
most common language
used for creating and querying relational databases
has 3 types of commands:
DDL
DML
DCL
DDL data definiton language?
commands used to define a database
creating, altering, deleting tables
establishing constraints
DML data manipulation language
commands used to maintain and query a database
updating, inserting, modifying, querying
DCL data control language
commands used to control a database
controlling users privileges
- read and write, read only
Types of database structures in database system
HOROND
Hierarchical Object-oriented Relational Object-relational Networked Distributed
Hierarchical database structure?
data elements at one level
own the data elements at next lower level
organizational chart
Networked database structure
each data element has several owners and
own several other elements
matrix style
Relational database?
logical structure of a group of related spreadsheets
each row represents a record
each column represents a field common to all records
row - accumulation of all fields related to the same identifier or key
Object-oriented database?
information are included in object classes
Object-relational database?
has relational and object-oriented features
Distributed database?
single database
spread physically across computers in multiple locations
connected by data communications link
Structure is frequently:
relational
object-oriented
object-relational
Composition of database controls?
U A BAD
User department Access controls Back-up and recovery Database administrator Audit software
User department - database control?
strict control access to system
control over terminals
read and write, or read only
Access controls?
controls within the database itself
limit the user to reading and/or updating only
Restricting privileges?
limits access of users - particular operation a user can perform
Logical views?
authorized views only of a database portion
Back up and recovery as database control?
continuous daily updating of database
3 types:
backup of database and logs of transactions
database replication
backup facility
Backup of database and logs of transactions?
Systems logs
backup several times a week
generally to magnetic tape
maintain transactions log
in case of major damage:
use the most recent past copy
to reconstruct to the most current state
redo transactions from log up to point of failure
Database replication?
to avoid catastrophic failure
replicate the database
at one or more locations
by recording all data to both sets
Backup facility?
maintain a backup facility
vendor who will process data
in case of emergency
Database administrator?
DBA
maintains the database
restricts access to authorized personnel
Audit software?
used by auditors
to test the database
Advantages of database systems?
Data independence Minimal data redundancy Data sharing Reduced program maintenance Modification if using commercial applications
Data independence?
different applications can use data easily
Minimal data redundancy?
recording of information in one place
updating is easier
better than traditional file systems
Data sharing?
easy data sharing between individuals and applications
Disadvantages of database systems?
needs expert personnel
costly installation
costly conversion from traditional file system
requires comprehensive backup and recovery
Methods of DISTRIBUTING relational database across multiple servers:
Snapshot
Replication
Fragmentation
What is snapshot?
making a copy of the database
for distribution
What is Replication?
creating and maintaining replica copies
at multiple locations
Fragmentation?
separating the database into parts
distributing where they are needed
Methods of DESIGNING a relational database:
Normalization
Normalization?
method of designing a relational database
separating the database into logical tables
for easier user processing
Disadvantages/security concerns of DISTRIBUTED data processing:
Password proliferation -
users tempted to write down passwords
or make them very simple
Difficulty in developing uniform security standards
Advantage of decentralized/distributed data processing
lesser risk of a destroying large data due to a single disaster
What are Fourth Generation Programming?
instructions close to human language
What is First Generation Programming?
machine language
binary language
instructions using 0s and 1s
Hierarchy of data organization is BBFRTD
bit byte field record table database
Decision support system?
online analytical processing
represents a combination of systems
aggregate, analyze business data
assist in business decision making process
What is the 2nd generation programming language?
Assembly language
uses words and mnemonics
What is the 3rd level of programming language?
Object-oriented programs
Uses methods
Uses concepts of class and inheritance
COBOL C++
What is Virtualization software?
allows a single computer
to run multiple operating systems simultaneously
lower computer hardware costs
reduce energy costs
Digital approach of computer processing
format of computer processing of data
represent information by numerical digits
Compiler?
decodes instructions written in a higher order language
converts is to assembly language program
