Chapter 12
Information system
Software that helps the user organize and analyze data
Electronic spreadsheets and database management systems
Software tools that allow the user to organize, manage, and analyze data in various ways
Spreadsheet
A software application that allows the user to organize and analyze data using a grid of labeled cells
– A cell can contain data or a formula that is used to calculate a value
– Data stored in a cell can be text, numbers, or “special” data such as dates
– Spreadsheet cells are referenced by their row and column designation
The power of spreadsheets comes from the formulas that we can create and store in cells
– When a formula is stored in a cell, the result of the formula is displayed in the cell
– If we’ve set up the spreadsheet correctly, we could
• add or remove tutors.
• add additional weeks of data.
• change any of the data we have already stored and the corresponding calculations would automatically be updated.
– Formulas make use of basic arithmetic operations using the standard symbols (+, -, 2, *, and /)
–
Spreadsheet functions
–
Computations provided by the spreadsheet software that can be incorporated into formulas
–
Range
–
A set of contiguous cells specified by the endpoints
Circular reference
A set of formulas that ultimately rely on each other
Possible tasks a spreadsheet could perform:
• Track sales
• Analyze sport statistics
• Maintain student grades
• Keep a car maintenance log
• Record and summarize travel expenses
• Track project activities and schedules
• Plan stock purchases
• Spreadsheets are also useful because of their dynamic nature, which provides the powerful ability to do what-if analysis
•
Database
•
A structured set of data
•
Database management system (DBMS)
•
A combination of software and data, made up of a physical database, a database engine, and a database schema
•
Physical database
•
A collection of files that contain the data
•
Database engine
•
Software that supports access to and modification of the database contents
•
Database schema
•
A specification of the logical structure of the data stored in the database
•
Database query
•
A request to retrieve data from a database
Relational DBMS
A DBMS in which the data items and the relationships among them are organized into tables
Tables
A collection of records
Records (object, entity)
A collection of related fields that make up a single database entry
Fields (attributes)
A single value in a database record
Key
One or more fields of a database record that uniquely identifies it among all other records in the table
We can express the schema for this part of the database as follows:
Movie (MovieId:key, Title, Genre, Rating)
Structured Query Language (SQL)
A comprehensive relational database language for data manipulation and queries select attribute-list from table-list where condition name of field name of table value restriction select Title from
Movie
where Rating = 'PG'
Result is a table containing all PG movies in table Movie
Entity-relationship (ER) modeling
A popular technique for designing relational databases
ER Diagram
A graphical representation of an ER model
Cardinality constraint
The number of relationships that may exist at one time among entities in an ER diagram
Electronic commerce
The process of buying and selling products and services using the Web.
Chapter 16
The Web
An infrastructure of information combined and the network software used to access it
Web page
A document that contains or references various kinds of data
Links A connection between one web page and another
Website
A collection of related web pages
Web browser
A software tool that retrieves and displays eb pages
Web server
A computer set up to respond to requests for web pages
Uniform Resource Locator (URL)
A standard way of specifying the location of a Web page, containing the hostname, "/", and a file
Instant messaging (IM)
An application that allows people to send and receive
