Friday, July 19, 2013

                                 Storing Organizational Information

                                    what is the information
                      Information is everywhere in an organization

                               Information is stored in databases
 Database – maintains information about various types of objects (inventory), events (transactions), people (employees), and places (warehouses)

                            •Database models include:

Hierarchical database model – information is organized into a tree-like structure (using parent/child relationships) in such a way that it cannot have too many relationships
Network database model – a flexible way of representing objects and their relationships
Relational database model – stores information in the form of logically related two-dimensional tables

            •Entity – a person, place, thing, transaction, or event about which information is stored
The rows in each table contain the entities
In Figure 7.1 CUSTOMER includes Dave’s Sub Shop and Pizza Palace entities

            •Attributes (fields, columns) – characteristics or properties of an entity class
The columns in each table contain the attributes
In Figure 7.1 attributes for CUSTOMER include Customer ID, Customer Name, Contact Name

                      •Keys and Relationships
           Primary keys and foreign keys identify the various entity classes (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

Database advantages from a business perspective include
Increased flexibility
Increased scalability and performance
Reduced information redundancy
Increased information integrity (quality)
Increased information security

Increased Flexibility

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