Architecture and Basics Flashcards
Data vs Information
Data is raw facts and figures. This is the atomic pieces of information.
Information is the processed form of data. Information is the collected form of data. Example Ron - 23 years old.
What is a schema
It’s a map of of logical structure of a database. It’s also called the intension of a database.
The instance of a database is sometimes referred to as extension of a database.
External Level vs Conceptual Level vs Internal Level
External Level -> It is the users view of the database, this describes the information that is relevant to users.
Conceptual Level -> This is the community view of the database. This level describes what information is stored in the database and the relationship between the data stored. It represents all the entries and their attributes. Constrains and security information.
Internal Level -> This level is the physical information of the database, this contains storage space allocation, data encryption details, data compression and the record placements.
Define Logical and Physical data Independency.
Logical Data Independency -> This indicates that the logical or the conceptual data can be changed or modified without affecting the external or the user level data. Modification of the conceptual level is necessary whenever the logical level is altered.
Physical Data Independency -> Physical data independence indicates that the physical storage structures or devices could be changed without affecting conceptual schema.
