lesson 3 database

Question 1

Only addresses data and
relationships. Best for deriving a sound table
design.

Answer 1

Entity-Relationship (E-R) Model

Question 2

Class models. Goes beyond data, also models
behaviors.

Answer 2

UML (unified modeling language)

Question 3

Technology independent. Contains more detail than the Conceptual Data Model. Considered by many to be just an expanded conceptual data model. Entities AND their attributes. Relationships AND cardinality. Constraints.

Answer 3

Logical Data Model

Question 4

Documentation of the structure of the data. Used to communicate the design. Serve as the basis for data model implementation.

Answer 4

Entity Relationship Model

Question 5

Entities effectively become tables. Attributes describe entities and become fields (columns) in tables. Relationships link tables on a common attribute or “key” and become formal constraints (part of the business rules).

Answer 5

Entity Relationship Diagram

Question 6

Multiple notation systems are used. Each software program is a little different. Most common is “Crows Foot”.

Answer 6

ER Diagram Relationship Notation

Question 7

maximum number of times an instance in one
entity can be associated with instances in the related entity

Answer 7

Cardinality

Question 8

minimum number of times an instance in one
entity can be associated with instances in the related entity

Answer 8

Participation

Question 9

Each row in a table should have an attribute that is a
persistent, unique identifier–

Answer 9

the “Primary Key”

Question 10

Collection of Tables.
Tables represents both data and relationships
Multiple columns with unique names.
Tables = Relations
Record-based model – fixed format records of several types
Each record type defines a fixed number of fields, or attributes
Most widely used db.

Answer 10

Relational Model

Question 11

Collection of basic objects called entities and its relationships.
An entity is a real world thing or object
Distinguishable from other objects
Widely used in database design

Answer 11

Entity-Relationship Model

Question 12

Need for Object Oriented data model.
Object Based Model = ER model and Object Oriented Features
Object Relational Data Model = Object Based Model+ Relational Model

Answer 12

Object-Based Model

Question 13

Specification of data
Individual data items of the same type may have different sets of attributes
Using of 2 different language
Contrast to ER Model, Relational Model and Object Oriented Model
XML

Answer 13

Semistructured Data Model