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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