What is databases ?
Maintain info about various types of objects (inventory), event (transaction),
people (employees) and places (warehouses).
For example UiTM student portal and facebook
Relational Database Fundamental
Entity and Attribute
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 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 and Attribute
- Entity - A person , place, thing, transaction, or event about which information is stored.
- Attributes (field, columns) - characteristics or properties of an entity class.
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 identifys a given entity in a table.
- Foreign key - a primary of one table that appears an attribute in another table and acts to provide a logical relationship among the two tables.
Relational Database Advantages
Database advantages from a business perspective include :
- Increased flexibility
- Increased scalability and performance
- Reduced information integrity (quality)
- Increased information redundancy
- Increased information security
Increased flexibility
A well-designed database should:
- Handle changes quickly and easily
- Provide users with different views
- Have only physical view - deals with the physical storage of information on a storage device
- Have multiple logical 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 tp increased demands
- Performance : measures how quickly a system performs a certain process or transaction
Reduced Information Redundancy
- Databases reduce information redundancy - The duplication of information or storing the same information in the multiple places.
- Inconsistency is one of the primary problems with redundant information.
Increased Information Integrity (Quality)
- Information integrity : measures the quality of information
- Integrity constraint : rules that help ensure the quality of information
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