Computer 10

Database
a collection of data organized in a manner that allows access, retrieval, and use of that data.
Data
a collection of unprocessed items
Information
is processed data; that is, it is organized, meaningful, and useful.
Database software
also known as database management system (DBMS), users create a computerized databases; add, modify, and delete data in the databases; sort and retrieve data from the database; and create forms and reports from the data in the database.
Data integrity
identifies the quality of the data.
Garbage in, Garbage out
(GIGO) is a computing phrase that points out the accuracy of a computer’s ouput depends on the accuracy of the input.
Variable information
information must be accurate, verifiable, timely, organized, accessible, useful, and cost-effective.
Character
represented by 1 byte which can be a number, letter, space, punctuation mark, or other symbol.
Field
a combination of one or more related characters or bytes and is the smallest unit of data a user accesses.
Field name
uniquely identifies each field.
Field size
defines the maximum number of characters a field can contain.
Data type
specifies the kind of data a field can contain and how the field is used. ex: numerical, yes/no…
Record
a group of related fields
Primary key
a field that uniquely identifies each record in a file.
Data file
a collection of related records stored on a storage medium such as a hard disk or optical disc.
File maintenance
refers to the procedures that keep data current. procedures include adding records to modifying records in, and deleting records from a file.
Validation
is the process of comparing data with a set of rules or values to find out if the data is correct.
Validity check
analyzes data either as you enter it or after you enter it, to help ensure that it is correct.
Alphabetic/numeric check
check that only letters or numbers are entered.
Range check
determines whether a numbers within a specified range.
Consistency check
tests the data in two or more associated fields to ensure that the relationship s logical and their data is in the correct format.
Completeness check
verifies that a required field contains data.
Check digit
is a number(s) or character(s) that is appended to or inserted in a primary key value.
DBMs hyperlink check
can check hyperlink and attachment data for validity.
File processing system
each department or area within an organization has its own set of files. Cons: data redundancy, isolated data
Database approach
many programs and users share the data in the database.
front end: a program that generally has a more user-friendly interface than the DBMs
back end: an application that supports a font-end program
pros: reduced data redundancy, improved data integrity, shared data, easier access, reduced development time.
cons: more complex, require more memory, storage, and processing power.
Data dictionary
sometimes called a repository or metadata, contains data about each file in the database and each field in those files.
contains data about programs and user.
default value: a value that the DBMS initially displays in a field.
query
a request for specific data from the database.
Four most commonly used: query languages, query by example, forms, and report generators.
Query language
consists of simple, English-like statements that allow users to specify the data to display, print, or store.
Query by example
(QBE) a feature that has a graphical user interface to assist users with retrieving data.
Form
sometimes called a data entry form, is a window on the screen that provides areas for entering or modifying data in a database.
Electronic form
a form that sends entered data across a network or the internet.
Report generator
also called a report writer, allows users to design a report on the screen, retrieve data into the report design, and then display or print the report. Unlike a form, you use a report generator only to retrieve data.
Access privilege
for data involve establishing who can enter new data, modify existing data, delete unwanted data, and view data.
Principle of least privilege policy
where users access privileges are limited to the lowest level necessary to perform required tasks.
Backup
a copy of the database that should be made on a regular basis.
Log
a listing of activities that modify the contents of the database.
1) a copy of the student record prior to the change, called the before image 2) the actual change of address data 3) a copy of the student record after the change, called the after image.
Recovery utility
uses the log an/or backups to restore a database when it becomes damaged or destroyed.
Rollforward
forward recovery, the DBMS uses the log to reenter changes made to the database since the last save or backup.
Rollback
backward recovery, the DBMS uses the log to undo any changes made to the database during a certain period.
Continuous backup
a backup plan in which all data is backed up whenever a change is made.
Data model
consists of rules and standers that define how the database organizes data. A data model defines how users view the organization of data.
Object-relational database
combine features of the relational and object-oriented data models.
Relational database
is a database that stores data in tables that consist of rows and columns.
Developer refers to a file as a relation, a record as a tuple, and afield as an attribute.
Users refer to a file as a table, a record as a row, and a field as a column.
Can set up a relationship between tables at any time if they have a common column.
Best suited for two-dimensional table.
normalization is a process designed to ensure the data within the relations (tables) contains the least amount of duplication.
Structured query language
(SQL) is a popular query language that allows users to manage, update, and retrieve data.
Object oriented database
(OODB) stores data in objects.
Object is an item that contains data, as well as the actions that read or process the data.
They can store more types of data, access this data faster, and allow programmers to reuse objects.
Ex: multimedia database, groupware database, computer-aided design (CAD) database, hypertext database.
Object query language
object-oriented and object-relational databases often use the query.
multidimensional database
stores data in dimensions. Also known as hypercube, allows users to access and analyze any view of the database data.
The content of other dimensions varies depending on the subject.
The key advantage of the multidimensional database is that I can consolidate data much faster than a relational database.
Data warehouse
is a huge database that stores and manages the data required to analyze historical and current transactions.
Distributed database: exists in many separate locations throughout a network or the internet.
Data mining
Data mart: smaller version of a data warehouse.
Collaborative databases
makes up some web database. users store and share photos, videos, recordings, and other personal media with other registered users.
The web page is the front end to the database.
Database server: is a computer that stores and provides access to a database.
Common Gateway Interface (CGI): one type of program that manages the sending and receiving of data between the front end and the database server.
Database analyst
(DA) or date modeler, focuses on the meaning and usage of data, decided on the proper placement of fields, defines the relationships among data, and identifies users’ access privileges.
Database administrator
(DBA) creates and maintains the data dictionary, manages security of the database, monitors the performance of the database, and checks backup and recovery procedures.