Flashcards in Information Management and BI 1(b) (Part 2) Deck (6):
What are 3 types of "Schema" Levels?
- Data can be structured using these standard schemas:
(1) External or User
(2) Conceptual or Logical
(3) Physical or Internal
What is a "User/External Schema"?
- User's perspective or view of data
- External view means perspective of data from external sources
- Compile composite view representing all needs, associated w/ info req'mts
- Ex: Provide what databases, files, records, fields a user or user grp have access, and if access is read-only (RO) or read-write (RW)
What is a "Conceptual/Logical Schema"?
- Once External Schema is complete, composite of all external views or schema developed to represent entity's view or schema or composite users' view (or "Conceptual Schema")
- Exists only on paper or digital but prescribes format of database(s) w/ specificity of data to be captured, stored and processed at enterprise level
What is a "Physical/Internal Schema"?
- When Conceptual Schema is implemented via a Database Mgmt Sys (DBMS) onto a
physical computer, known as the "Physical Schema"
- DBA formats databases, files and fields to define all data to be captured in
that particular system properly
Describe a "Data Hierarchical Structure" from smallest to largest segment:
(1) BIT - (0 or 1), Binary digit form
(2) BYTE - Keystroken = 1 Byte = 8 Bits
- (letter, number or special character)
(3) FIELD - Column
- Data Value, grp characters, attribute
(4) RECORD - Row
- Data set values, collection of attributes
(5) FILE - Table
- Set of related Records
(6) DATABASE - Set of related Files
(7) ENTERPRISE DATABASE
- Set of databases
- Ex: AR, AP