- information is everywhere in an organization
- information is stored in databases
- databases - maintains information about various types of objects (inventory), events (transaction), people )employee), and places (warehouse)
- database includes includes:
- hierarchical database model - information is organized into a tree-like structure (using parent/child relationships) in such way that it cannot have too many relationships
- network database model - a flexible way of representing object and their relationships
- 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
- attributes (fields, columns) - characteristics or properties of an entity class
- the column in each table contains the attributes
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 tables
- 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 database
- database advantage from a business perspective include
- increased flexibility
- increased scalability and performance
- reduced information redundancy
- increased information integrity (quality)
- increased information security
increased flexibility
- a well- designed database should:
- handle changes quickly and easily
- provide users with different views
- have only one physical views
- have multiple logical views
- logical view - focuses on how users logically access information
- eg: a mail-order buss-2 people view diff format (logical views) but same physical view
increased scalability and performance
- a database must scale to meet increased demand, while maintaining acceptable performance levels
- scalability - refers to how well a system can adapt to increased demand
- performance - measures how quickly a system performs a certain process or transaction
reduced information redundancy
- databases reduce information redundancy
- redundancy - the duplication of information or storing the same information in multiple places
- inconsistency is one of the primary problems with redundant information
- difficult to decide which is most current and most accurate
increased information integrity (quality)
- information integrity - measures the quality of information
- integrity constraints - rules that help ensure the quality of information
- relational integrity constraint - rule that enforces basic and fundamental information-based constraints
- Eg. users cannot create an order for a nonexistent customer, provide a markup percentage that was negative etc.
- business critical integrity constraint - rule that enforce business rules vital to an organization's success and often require more insight and knowledge than relational integrity constraints
- Eg. product returns are not accepted for fresh product 15 days after purchase
increased information security
- information is an organization asset and must be protected
- database offer several security features including:
- password - provide authentication of the user
- access level - determines who has access to the different types of information
- access control - determines types of user access, such as read-only access
Database management system
- database management system (DBMS) - software through which user and application programs interact with a database
Data driven web sites
- data driven websites - an interactive web site kept constantly updated and relevant to the needs of its customers through the use of a database
- advantages
- development: allows the websites owner to make changes anytime - all without to rely on a developer or knowing HTML programming. a well-structured, data web site enables updating with little or no training.
- content management: a static web site requires a programmer to make updates. this adds an unnecessary layer between the business and its wen contract, which can lead to misunderstanding and slow turnarounds for desired changes.
- future expandability: having a data driven web site enables the site to grow faster than would be possible with a static site, changing the layout, displays, and functionality of the site (adding more features and section) is easier with a data driven solution
- minimizing human error: even the most competent programmer charged with the task of maintaining many pages will overlook things and make mistakes. this will lead to bugs and inconsistencies that can be time consuming and expensive to track down and fix. unfortunately, uses who come across these bugs will likely become irritated and may leave the site. a well-designed, data driven web site will have "error trapping" mechanisms to ensure that required information is filled out correctly and that content is entered and displayed in its correct format.
- cutting production and update costs: a data driven web site can be updated and "published" by any competent data entry or administrative person. in addition to being convenient and more affordable, changes and updates will tak a fraction of time that they would with a static site. while training a competent programmer can take months or even a years, training a data entry person can be done in 30-60 minutes
- more efficient: by their very nature, computers are excellent as keeping volumes of information intact. with a data driven solution, the system keeps track of the templates, so users do not have to. global changes to layout, navigation, or site structure would need to be programmed only once, in one place, and the site itself will take care of propagating those changes to the appropriate pages and areas.
- improved stability: any programmer who has to update a web site from "static" templates must be very organized to keep track of all the sources files. if a programmer leaves unexpectedly, it could involve re-creating existing work if those source file cannot be found.
- plus. if there were any changes to the templates, the new programmer must be careful to use only the latest version. with a data driven web site, there is peace of mind, knowing the content is never lost.
integration information among multiple database
- integration - allows separate system to communication directly with each other
- forward integration - takes information entered into a given system and sends it automatically to all downstream systems and processes
- backward integration - takes information entered into a given system and sends it automatically to all upstream systems and processes.
- building a central repository specifically for integrated information
- without integration, an organization will:
- spend considerable time entering the same info in multiple system
- suffer from the low quality and inconsistency typically embedded in redundant info.
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