- 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).
- 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.
Entities and Attributes
- Entity is a person, place, thing, transaction, or event about which information is stored (The rows in each table contains the entities).
- Attributes is characteristics or properties of an entity class (The columns in each table contain 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 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
A) Increased flexibility
A well-designed database should;
- Handle changes quickly and easily
- Provide users with different views
- Have only one physical views
- Physical view – deals with the physical storage of information on a storage device
- Have multiple logical views
- Logical view – focuses on how users logically access information
B) 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 demands
- Performance – measures how quickly a system performs a certain process or transaction
C) 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
D) Increased information integrity (quality)
- Information integrity – measures the quality of information
- Integrity constraint – 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 ; An order cannot be shipped without an address
E) Increased information security
- Information is an organization asset and must be protected
- Databases offer several security features including;
- Password – provides 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 Systems
A database management systems (DBMS) is software through which users and application programs interact with a database.
A data-driven website is an interactive website keep constantly updated and relevant to the needs of its costumer through the use of a database.
Data-Driven Website Advantages
- Development : Allows the website owner to make changes any time
- Content management : A static website requires a programmer to make updates.
- Future expandability : Having a data-driven website enables the site to grow faster than would be possible with a static site.
- Minimizing human error
- Cutting production and update costs
- More efficient
- Improved stability
Integrating Information among Multiple Databases
An integration allows separate systems to communicate directly with each other.
- A forward integration takes information entered into a given system and sends it automatically to all downstream processes.
- A backward integration takes information entered into a given systems and sends it automatically to all upstream systems and processes