Storing Organizational Information
- the computer program used to manage and query a databases is known asa database management system (DBMS).
- the central concept of a database is that of a collection of records,or pieces of information.
- typically a given database has a structural description of the type of facts held in that database:
-this description is known as a schema.
-the schema describes the objects that are represented in the database and the relationships among them.
-there are a number of different ways of organizing a schema,that is,of modeling the database structure:
- these are known as data base models(or data models)
- the most commonly used model today is the relational model
- other models,such as the hierarchical model,and network model,use a more explicit representation of relationships.
Relational Database Fundamentals
- a database maintains information about various types of objects(inventory),events(transactions),people(employees),places(warehouses).
- hierarchical database model,information is organized into a tree like structure that allows repeating information using parent/child relationships in such way that it cannot have too many relationships.
- the network database model is a flexible way of representing objects and their relationships.
- the relational database model is a type of database that stores information in the form of logically related two-dimensional tables.
Entities and Attributes
- entity in the relational database model is a person,place,thing,transaction,or event about which information is stored.
- attributes also called fields or columns,are characteristics or properties of an entity class.
Keys and Relationships
- to manage and organize various entity classes within the relational database model,develops must identity primary keys and foreign keys and use them to create logical relationships.
- a primary keys is a field(or group of fields) that uniquely identifies a given entity in a table.
- a foreign key in the relational database model is a primary key of one table that appears as an attribute in another table and acts to provide a logical relationship between the two tables.
Relational Database Advantages
- from a business perspective database information offers many advantages,includng:
-increased flexibility
-increased scalability and performance
-reduced information redundancy
-increased information integrity(quality)
-increased information security
Increased Flexibility
- the physical view of information deals with the physical storage of information on a storage device such as hard disk.
- the logical view of information focuses on how users logically access information to meet their particular business needs.
Increased Scalability and Performance
- scalability refers to how well a system can adapt to increased demands.
- performance measures how quickly a system performs a certain process or transaction
Reduced Information Redundancy
- redundancy is the duplication of information,or storing the same information in multiple places.
Increased Information Integrity(Quality)
- information integrity is a measure of the quality of information.
- integrity constraints are rules that help ensure the quality of information
- can be defined and built into the database design.
- the database(more appropriately,the database management system,which is discussed below)ensures that users can never violate these constraints.
- there are two types of integrity constraints:
-relational integrity constraints and business critical integrity constraints
- relational integrity constraints are rules that enforce basic and fundamental information-based constraints.
- business-critical integrity constraints enforce business rules vital to an organization's success and often require more insight and knowledge than relational integrity constraints.
Increased Information Security
- access levels determine who has access to the different types of information,and access controls determine what type of access they have to the information.
Database Management Systems
- database management system(DBMS) is software through which users and application programs interact with a database.
Interacting Directly and Indirectly with a Database through a DBMS
Data-Driven Websites
- the pages on website must change according to what a site visitor is interested in browsing.
- data-driven websites is an interactive website kept constantly updated and relevent to the needs of its customers through the use of a database.
Data-Driven Website Business Advantages
Data-Driven Business Intelligence
Integrating Information among Multiple Databases
- without integration,an organization will spend considerable time entering the same information in multiple systems and suffer from the low quality and inconsistency typically embedded in redundant information.
- a forward integration takes information entered into a given system and sends it automatically to all downstream systems and processes.
- a backward integration takes information entered into a given system and sends it automatically to all upstream systems and processes.
A Forward and Backward Customer Information Integration Example
Integrating Customer Information among Databases
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