Data Models Flashcards
This is the description of a database. Includes description of the database structure, data types, and the constraints on the database.
Database Schema
It is an illustrative display of (most aspects of) a database schema
Schema Diagram
It is a component of schema or an object within the schema, e.g, STUDENT, COURSE
Schema Construct
It is the actual data stored in a database at a particular moment in time
It also includes the collection of all the data in the database
Database State
A database state is also called as?
database instance or occurrence or snapshot
In a database state, this refers to the database state after defining a new database
Empty State
In a database state, this refers to the database state when the database is first populated or loaded with initial data
Initial State
In this database state, it is a state that satisfies the structure and constraints of the database at any point in time. Also known as the current state.
Valid State
Database Schema or Database State?
This database changes infrequently.
Database Schema
Database Schema or Database State?
Changes every time the database is updated
Database State
A schema is also called?
intension
A state is also called?
extension
It is a collection of concepts used to describe the structure of a database and the operations for manipulating these structures
Data Model
—— of a database includes datatypes, relationships, and constraints.
Structure
—– specify some restriction on valid data; these constraints must be enforced at all times.
Constraints
In the categories of data models, this refer to (high-level, semantic) data models. It provides concept that are close to the way many users perceive data.
conceptual
In the categories of data models, this refer to (low-level, internal) data models. Provides concepts that describe details of how data is stored in the computer. It is generally meant for computer specialists and not for typical end-users
physical
In the categories of data models, this refer to (representational) data model. Provide concepts that fall between the physical and conceptual, used by many commercial DBMS implementations.
Implementation
This category of data model is also called as an entity based or object-based data models
Conceptual
