Lecture 3

Question 1

Describes database structure: data types, relationships, constraints.

Specifies retrieval and update operations.

Increasingly includes dynamic aspects of database applications.

Answer 1

Data Model

Question 2

Provide concepts that are close to the way many users perceive data (Also called entity-based, object-based data models)

Answer 2

Conceptual (high-level)

Question 3

Provide concepts that describe details of how data is stored in the computer

Answer 3

Physical (low-level)

Question 4

Provides concepts that may be understood by end users but that are not too far removed from the way data is organized within the computer

Hide some details of data storage but can be implemented on a computer system in a direct way

Answer 4

Implementation (representational)

Question 5

The description of a database.
Not expected to change frequently

Answer 5

Database Schema (intension)

Question 6

A diagrammatic display of (some aspects of) a database schema.

Answer 6

Schema Diagram

Question 7

The data in the database at a particular moment of time. Also called the current set of occurrences or instances.
Every update operation changes the database from one state to another

Answer 7

Database State (extension)

Question 8

Describes the physical storage structure
Uses a physical data model

Answer 8

Internal Schema

Question 9

Describes the structure of the whole database Uses a conceptual or an implementation data model

Answer 9

Conceptual Schema

Question 10

Includes a number user views. Uses a conceptual or an implementation data model

Answer 10

External Schema

Question 11

The process of transforming requests and results between levels

Answer 11

Mappings

Question 12

The capacity to change the conceptual schema without having to change the external schema or application programs

Answer 12

Logical Data Independence

Question 13

The capacity to change the internal schema without having to change the conceptual schema

Answer 13

Physical Data Independence

Question 14

Defines conceptual schema by DBA and designers.

Also used to define the internal and external schemas

In some systems, separate SDL and VDL define internal and external schemas.

Answer 14

Data Definition Language (DDL)

Question 15

can be used as stand-alone (query language) or can be embedded within a general-purpose language

Answer 15

Data Manipulation Language (DML)

Question 16

allows user to tell system exactly how to manipulate data

Answer 16

Procedural DML

Question 17

allows user to state what data is needed rather than how it is to be retrieved

Answer 17

Non-Procedural DML

Question 18

DBMS Interfaces

Answer 18

Menu-based
Forms-based
Graphical User
Natural Language
Interfaces for Parametric Users
Interfaces for The DBA

Question 19

Database System Utilities

Answer 19

Loading
Backup
File Reorganization
Performance monitoring
Handling data compression
Monitoring access by users

Question 20

Classification of DBMSs

Answer 20

Data Model
Number of Users
Number of Sites
Cost
Types of Access Path
Purpose

Question 21

Used in the design phase

Answer 21

CASE tools

Question 22

Stores catalog information about schemas and constraints
Stores other information such as design decisions, usage standards, application program descriptions, and user information

Answer 22

Expanded Data Dictionary(information repository)

Question 23

Provide an environment for developing database applications
Include facilities for database design, GUI development, querying and updating, and application program development

Answer 23

Application Development Environments

Question 24

Allow users to access database from remote location

Answer 24

Communications software