B2tween Creativity & Safety

•Two or more tables that are linked together through common fields

•Each table in can be joined with more than one table

•Each row called a tuple

•Each column has an allowable set of values called a domain

Entity Relationship modeling

•A database is a collection of entities

•Entities contain properties called attributes - example - “title” for books

•Relationship relate entity classes

Purpose of Attributes

•Describe important properties of entity

•Help uniquely identify individual entities

▫ this is the primary key

▫ publisher id number, customer id number

•Describe relationship between entities in different entity classes

Entity models to Relational Databases

•We implement the abstract ER model to create a concrete database

▫ entity classes transform to relations

▫ attributes transform to fields

▫ entity sets transform to rows or tuples in relations

▫ one-to-many relationships modeled with foreign keys

▫ many-to-many relationships modeled with new table schemes

Identify the entity 

Identify the A++ attribute - the primary key 

Identify relationships 

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Relational (Tables) Database Fundamentals
   * Information is everywhere in an organization   
   * Information is stored in databases 
   * Database – maintains information about
      * various types of objects (inventory),
      * events (transactions),
      * people (employees),
      * places (warehouses)   
   * Database models include: 
      * Hierarchical database model 
      * Network database model  
      * Relational database model
         * stores information in the form of logically related two-dimensional tables 

Entities and Attributes
   * Entity – a person, place, thing, transaction, or event about which information is stored 
      * The rows in each table contain the entities 
      * In Figure 6.5 CUSTOMER includes Dave’s Sub Shop and Pizza Palace entities   
   * Attribute (field, column) – characteristics or properties of an entity class 
      * The columns in each table contain the attributes 
      * In Figure 6.5 attributes for CUSTOMER include Customer ID, Customer Name, Contact Name

Keys and Relationships
Primary keys and foreign keys identify the various entities (tables) in the database 
   * Primary key – a field (or group of fields) that uniquely identifies a given entity in a table 
   * Foreign key – a primary key of one table that appears an attribute in another table and acts to provide a logical relationship among the two tables 

Relational Database Advantages
   * Increased flexibility 
   * Increased scalability and performance 
   * Reduced information redundancy 
   * Increased information integrity (quality) and information security 

Relational Database Disadvantages
   * High cost
   * Specialized staff
   * Increased vulnerability

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Generating revenue on the Internet  
   * Online ad (banner ad) - box running across a web page that contains advertisements 
   * Pop-up ad - a small web page containing an advertisement  
   * Associate program (affiliate program) - businesses generate commissions or royalties  
   * Viral marketing - a technique that induces websites or users to pass on a marketing message 
   * Mass customization - gives customers the opportunity to tailor products or services (Dell computers)



Online business payments include: 
   * Electronic data interchange (EDI)  
   * Value-added network (VAN)  
   * Financial EDI (financial electronic data interchange)

Measuring e-business success
   * Most companies measure the traffic on a website as the primary determinant of the website’s success   
   * However, a large amount of website traffic does not necessarily equate to large sales   
   * Many organizations with high website traffic have low sales volumes 
   * Website traffic analysis can include:  Cookie, Click-through, Banner ad, Interactivity

Ebusiness benefits include: 
   * Highly accessible  
   * Increased customer loyalty 
   * Improved information content  
   * Increased convenience 
   * Increased global reach  
   * Decreased cost  

Ebusiness challenges include: 
   * Protecting consumers 
   * Leveraging existing systems 
   * Increasing liability
   * Providing security 
   * Adhering to taxation rules

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