What is the definition of data?
Known facts stored and recorded
Example:
Text, numbers, dates, plus images, sound, video, and other complex objects
What is information?
Data presented in context (can be summarised data) *
What is metadata?
Metadata is data about data
Example: Username length constraints
- can include: structure, rules, constraints
Why do we need metadata?
- Consistency
- Meaning
What is the definition of database
A large, integrated, structured collection of data.
Usually intended to model some real-world enterprise
Examples of databases
- A university
a. Entities - courses, students, professors
b. Relationships - enrolment, teaching - A social media site
a. Entities - posts, users, photos
b. Relationships - users like posts, users follow users, users edit photos
What is the definition of DBMS (Database Management System)
A software system designed to store, manage, and facilitate access to databases
What are the advantages of database?
- Data independence
- Minimal data redundancy
- Improved data consistency
- Improved data sharing
-Reduce program maintenance - Novel ad hox data access ‘without programming’
What is data independence?
- Separation of data and program, application logic
- Central data repository, central management
What is minimal data redundancy?
Redundancy can be controlled (normalization)
What is improved data consistency?
Single store: no disagreements, update problems, less storage space
What is improved data sharing?
- Data is shared, a corporate resource, not a necessity for an application
- External users can be allowed access
- Multiple views of data, arbitrary views of data
What is reduce program maintenance?
Data structure can change without application data changing
What is novel ad hox data access ‘without programming’
SQL
What is the point of using metadata?
To generate a data dictionary as part of the analysis of system requirements
What can database systems do?
- Manage data in a structured way
- Many models (hierarchical, network, etc), but relational dominant since ~1980
- Relational Model
- Rows & Columns forming relations: Keys & Foreign Keys to link relations
What is wrong with this
