Information Systems And Databases Flashcards
Characteristics of Information systems
Organisation of data into Information
Analysis of Information to give knowledge
What are the types of information systems
Transaction processing systems
Decision Support Systems
Expert systems
Managment information systems
Office automation systems
What is a Database
A database is an organised collection of data.
What are the four main advantages that Computer-based Databases have over non-computer databases
Easily edited
Large storage
Fast Retrieval
Display options
what are the four data structures of a database
File
Record
Field
Character
what are the two types of databases
Flat file databases and Relational databases
What are the four different types of Keys
Single key
Composite key
Primary key
Secondary key
what is a key
Keys are fields that are used to sort and retrieve information
What is a single key
a single key is a field in which each item of data is unique
what is a composite key
a composite key or also known as a compound key is made by joining two or more fields together.
what is a primary key
a primary key is a single key or compound key that must have a value
what is a secondary key
a secondary key is a field that contains useful items of data often used in searches.
what is a file
a file is a block of data.
what is a record
a record is a collection of facts about one specific entry in a database.
what is a field
a field is a specific category of data in a database
what is a character
a character is the smallest unit of data that people can use
What is a relational database
a relational database organises data using a series of related tables.
What is a flat file database
a flat file database organises data into a single table and is suitable for many small applications.
What is a schema
A schema is the data definition for a database. it is an organised plan of the entire database that shows how and where the data is found, descriptions of the data, and the data’s logical relationships. In relational databases schemas define the entities, attributes and relationships
what are the three things that Schema’s define in a relational database
entities
attributes
relationships
what is an entity
an entity is a specific thing about which information is collected and stored. In a flat file database there would be a separate file for each entity
what is an attribute
an attribute is a defined property of an entity, examples would include LastName, FirstName and PhoneNumber.
What is a relationship
a relationship is the way the entities are related to each other, in relational databases each entity are related using keys.
what are the four types of relationships
one-one
one-to-many
many-to-one
many-to-many
what is a one-to-one relationship
a one-to-one relationship occurs when each record in the first entity is related to exactly one record in the second entity
what is one-to-many or many-to-one relationship
a one-to-many relationship occurs when one record in the first entity is related to many records in the entity, but any record in the second entity relates to only on record in the first entity. Vice versa for many-to-one relationships
what is a many-to-many relationship
a many-to-many relationship occurs when each record in the first entity is related to many records in the second entity, and each record in the second entity is related to many records in the first entity.
what is a foreign key
a foreign key is an attribute(field) of a table that is a primary key of another table.
what is a table in a database
a table is the organisation of data into columns and rows, it is sometimes reffered to as a relation.
what is a row in a table also known as
tuple of an entity or one record.
what is a form
a form is used to view, enter, and change data in a table
what is data modelling
data modelling is the process of identifying entities, the relationships between those entities and the attributes of those entities. They are used to develop a schema for the database.
what are the three main tools used for data modelling
data dictionaries
schematic diagrams
normalisation
what are data dictionaries
a data dictionary is a comprehensive description of each field (attribute) in the database.
what are the characteristics of each item in a database
field name
field size
data type
field description
what is a field name
a field name is the name of the field
what is a data type
a data type (or field type) is the kind of data that can be stored in the field
what is the field size
field size or width is the number of characters allowed in each field.
what is a description in a data dictionary
description specifies the contents of a field
what is meta data
it is information about data
what is data redudancy
data redudancy is the undersiable duplication of data within a database
what is a Schematic diagram
Schematic diagrams are graphical tools that help define the database and develop a schema. A common schematic diagram is an entity-relationship diagram.
What is an Entity-relationship diagram (ERD)
an Entity-relationship diagram is a graphical method of identifying the entities and showing the relationship between them. It helps determine the data to be included in and excluded from the databases.
what is normalisation
Normalisation is the process of organising data into tables so that the results of using the database are unambiguous and as intended. It is a refinement process that aims to reduce data redundancy. Normalisation results in a database that is more efficent but more complex because the data is separated into more tables.
what are the degrees of normalisation
first Norm Form (1NF)
Domain/key normal form (DKNF)
what is first norm form
First norm form is moving data items into separate tables where the data in each table is a similar type. Each table is given a primary key.
What is a Domain/key normal form
A domain/key Normal form is a key uniquely identifies each row in a table. A domain is the set of permissible values for each attribute. This enforces key and domain restrictions to ensure that there are no problems when modifying the data base. DKNF is the final level of normalisation
what is Hypermedia
Hypermedia is a combination of media whose locations are linked electronically to provide an easy way to navigate between the information.
what is Hypertext
Hypertext is a system that allows documents to be cross-linked in such a way that the user can move from one document to another by clicking on a link
what is a link or hyperlink
a Link or hyperlink is indicated by a highlighted item (usually an under-lined word or a graphic) that allows an electronic connection.
what is a node
if another computer is the destination of the link that computer is what is known as a node.
What is a Uniform resource locator
A URL (Uniform resource locator) is the address of a file or resource on the Web. It is usually written in lower case, as a single unbroken line with no spaces.
what are the main parts of a URL
Protocol
Domain name
file path
what is a protocol in a URL
a protocol is the transfer method used to access a particular resource on the Web. In most casses the protocol will be ‘http://’ (hypertext transfer protocol)
what is a domain name
a domain name is the address of the specific computer where the resource is located such as ‘www.hi.com.au’ they can somtimes be replaced by the IP address.
what is a file path
a file path is the full path to the file to be retrieved. it may be a simple filename or it may be a directory path such as ‘atlas/about.htm’. The domain name and the file path are separated by a forward slash (/)
what is a Storyboard
a storyboard is a series of frames, each representing a different action or screen image. It is a tool used to organise hypermedia.
What are the four types of storyboard layouts
linear
hiearchical
non-linear
combination
what is a linear storyboard
a simple sequential path that is set up quickly
what is a hierarchical storyboard
a sequential path in a top-down design
what is a non-linear storyboard
it is a storyboard with no structure
what is a combination storyboard
it is the blending of the other types of storyboards
what is HTML
HTML is a set of special instructions that indicate how parts of a document will be displayed and navigated
what is an HTML editor
an HTML editor is a software program that specialises in writing HTML code
are HTML tags meta data
yes
how do you write HTML tags
a tag consists of a left angle bracket (<) a tag name and a right angle bracket (>)
the tags are usually paired for example <H1> and </H1> which indicates the start and and end of the instruction
the end tages are written similar to the start tage except with a slash (/) that precedes the text within the bracjets.
to write a hypertext-related tag it is <a> (which stands for the anchor) then a special instruction using HREF = ‘filename’ then (>) technology </a>
what is a database management system (DBMS)
a Database management system is a software package that allows users to access a database so they can enter, maintain and view the data.
what is the difference between a database and DBMS
a database contains the data whereas a DBMS provides access to the data.
how is data organised in a DBMS
In a DBMS data is organised into tables, viewed in forms, retrieved using queries and displayed in reports
how is data manipulated in a DBMS
a DBMS manipulates the data in many different ways such as sorting and searching
How can a DMBS help users to develop and maintain a database
organising the data using a data dictionary
showing relationships between entities using a schematic diagram
checking for identifable errors in a data entry
allowing flexibility to change the definition of the database
restricting access to the data to authorised people
providing information about the performance of the database.
what are the methods of acessing data
Sequential and direct access
what is sequential access
Sequential access occurs when data is accessed in a sequence. It is the only method used to access data stored on a magnetic tape. This method reads the beggining of the data until the required item is found. It does not require the exact location of the data item and is much slower than direct access and is impractical when immediate processing is required.
what is a direct access
Direct access occurs when data is accessed without accessing previous data items. Direct access uses the algorithim for where the data is stored to calculate the approximate location of the data, if it is not found at the location it continues searching until the desired data is accessed. Direct access often involves the use of an index which is called indexed access
what is index
an index is a table that contains information about the location of the data.
what is a distributed database
a distributed database is a database located at more than one site. It acts as a single collection of data but is geographicalled dispersed. Distrbuted databases reduce the data transmission costs however it makes it more more difficult to obtain a complete view fo the database.
what is a two phase commit
it is part of the DBMS used to maintain consistency across a distributed database
What is the difference between Online storage and offline storage
Online storage uses a peripher device that is under the user’s direct control, such as a hard disk on a personal computer. Where as Offline storage uses a peripheral device that is not under the user’s direct control such as a centralised database.
what are some peripheral storage devices and mediums
Hard disk
optical disc
Removeable cartridge
magnetic tape
what is a hard disk
a disk made of metal or glass and covered with magentic material. they are usually set up inside the computer’s case and the storage capcity is usually measured in GB. It uses direct access to retrieve data
what is an optical disk
a polycarbonate plastic disk with a reflective layer of metal covering the surface. Data is read and written using laser technology. Optical discs use direct acess to retrieve data.
types of otpical disks are CD-Rom and DVD
what is a removable cartridge
a hard disk encased in a metal or plastic cartridge and can be removed like a floppy disk. They are fast and used direct access.
two common types of removable cartridges are zip disks or jaz disks
what is a magnetic tape
a magnetic tape is a very long, thin strip of plastic coated with a thin layer of magnetic material. Magnetic tapes can store large quantities of data cheaply and are often used as a back up medium. They use sequential access to retrieve data.
What is Encryption
Encryption is the process of encoding code and decryption is the proces of changing it back (decoding). It is the most effective way to achieve data security durring the transmission of data.
what are the two main types of encryption
Asymmetric encryption
Symmetric encryption
what is the difference between Asymmetric encryption and Symmetric encryption
Asymmetric requires a key for encryption and a key for decription whereas Symmetric encryption requires the same key for both the encryption and decryption.
what is a back up
a back up is another copy of the data that can be used to rebuild the system
What are the three line of defenses in Data security
password
Firewall
Encryption
what are the two main methods of Sorting
Ascending: order from smallest to largest (0 to 9) or first to last (A to Z)
Descending: order from largest to smallest (9 to 0) or from last to first (Z to A)
what is a Query
a Query is a search of a database for records that meet a certain condition (it is a question you ask of the database)
what are the types of operators in a Search query
relational operators
Wildcard characters
logical operators
what is the difference between relational operators and wildcard characters
relational operators are characters or symbols indicating the relationship between two experessions. Examples relational operators are (=, <>, <, >, <=, >=)
wildcard characters represent one or more characters (? or *)
what is the difference between the ? and * wildcard characters
the * (asterisks) substitutes for any number of characters wheras the question mark (?) substitues for one character.
what is the difference between AND and OR operators
The AND operator requires both the first and the second query to be true whereas OR oeprators require either the first or second query to be true
what is SQL
Structured Query Language is a query language used to access and manipulate data in a relational database.
what is a query language
a specialised language to search a database.
what is a search engine
A search engine is a database of indexed Web sites that allow a keyword search.
what are directories
directories are lists of websites organised into categories such as computers, games or sport.
what is a search robot or spider
a search robot is a program that accesses web sites and gathers information for search engine indexes. They send back the URL of any document they find on the search engine’s indexing software and collects information such as titles and keyword from websites, and then indexes these words in a database.
what is a report
a report is the formatted and organised presentation of data. they are often based on a query.
what is the layout of a report
report header: appears once at the beginning of a report such as logo, report title and date.
page header: displays information such as a title, column heading or information needed at the top of every page.
details: section displays most of the information.
page footer: displays information such as the date, page number or any other information the user wants at the bottom of every page.
report footer: appears once at the end of the report
what are good design principles in a report
- headings that identify the purpose of the report
- layouts, such as tabular or column, that efficiently present the information
- text that is balanced on the page either vertically or horizontally
- styles that are consistent throughout the report and with its purpose
- columns that have clear and descriptive headings
- white space that is appropriately used to improve readability
- page numbers and the date included in the header or footer
what is a data source
the source of the data is the person or organisation that developed the data.
what is the accuracy of data
the accuracy of data is the extent to which it is free from errors
what is data validation
data validation is the check of the entry of data.
what are the types of data validation checks
Range check: is used if the data is restricted to a small range of particuar values
List check: is used when the data can be compared to a set of accepted data
Type check: is used to determine whether the data type is correct.
Check digit; is a digit calculated from the digits of code number and then added to that number as an extra digit.
what is data intergrity
Data integrity describes the reliability of the data. Reliable data is accurate, current and relevant.
what is privacy
the ability of an individual to control personal data.
what is a data warehouse
a database that collects information from different data sources. it is a storage area of raw data that can be analysed to assist organisations to make decisions. The contents of data warehouse are usually historical and static.
what is data mining
Data mining is a process that looks for relationships and patterns in the data stored in a database. It sorts through the data and turns up interesting and useful connections.
