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DBMS > Lecture 1 pt.2 > Flashcards

Lecture 1 pt.2 Flashcards

1
Q

A set of concepts to describe the structure of a database, the operations for manipulating these structures, and certain constraints that the database should obe

A

Data Model

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2
Q

Constructs define database structure.

Include elements (with data types) and groups (e.g., entity, record, table) with relationships.

Enforce data validity restrictions continuously.

A

Data Model Structure and Constraints

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3
Q

These operations are used for specifying database retrievals and updates by referring to the constructs of the data model

A

Data Model Operations

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4
Q

Categories of Data Models:

Provide concepts that are close to the way many users perceive data.

(Also called entity-based or object-based data models.)

A

Conceptual (high-level, semantic) data models

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5
Q

Categories of Data Models:

Provide concepts that describe details of how data is stored in the computer. These are usually specified in an ad-hoc manner through DBMS design and administration manuals

A

Physical (low-level, internal) data models

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6
Q

Categories of Data Models:

Provide concepts that fall between physical and conceptual data models, used by many commercial DBMS implementations (e.g. relational data models used in many commercial systems).

A

Implementation (representational) data models

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7
Q

The description of a database. Includes descriptions of the database structure, data types, and the constraints on the database

A

Database Schema

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8
Q

An illustrative display of (most aspects of) a database schema

A

Schema Diagram

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9
Q

A component of the schema or an object within the schema, e.g., STUDENT, COURSE

A

Schema Construct

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10
Q

The actual data stored in a database at a particular
moment in time. This includes the collection of all the data in the database

A

Database State

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11
Q

Also called database instance (or occurrence or snapshot).

A

Database State

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12
Q

Refers to the database state when it is initially loaded into the system

A

Initial Database State

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13
Q

A state that satisfies the structure and constraints of the database

A

Valid State

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14
Q

is also called intension

A

Schema

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15
Q

is also called extension

A

State

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16
Q

changes very infrequently

A

database schema

17
Q

changes every time the database is updated

A

database state

18
Q
  • Supports DBMS characteristics
  • Program-data independence.
  • Support for multiple data views.
  • Not widely implemented in commercial DBMS products.
  • Useful for explaining database system organization
A

Three-Schema Architecture

19
Q

Defines DBMS schemas at three levels

A

Three-Schema Architecture

20
Q

Three-Schema Architecture includes

A

Internal Schema
Conceptual Schema
External Schema

21
Q

describes physical storage structures and access paths (e.g indexes). Typically uses a physical data mode

A

Internal schema

22
Q

describes the structure and constraints for the whole database for a community of users.

A

Conceptual schema

23
Q

describes the various user views. Usually uses the same data model as the conceptual schema

A

External schemas

24
Q

The capacity to change the conceptual schema without having to change the external schemas and their associated application programs.

A

Logical Data Independence

25
Q

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

A

Physical Data Independence

26
Q

Used by the DBA and database designers to specify the conceptual schema of a database.

A

Data Definition Language (DDL)

27
Q

Used to specify database retrievals and updates

A

Data Manipulation Language (DML)

28
Q

Types of DML

A

High Level or Non-procedural Language

Low Level or Procedural Language

29
Q

Example: SQL relational language. “Set”-oriented, specifies what data to retrieve. Declarative.

A

High Level (Non-procedural) Language

30
Q

Retrieves data one record-at-a-time. Requires constructs like loops for multiple records retrieval. Involves positioning pointers.

A

Low Level (Procedural) Language

31
Q

is accessed by DBMS software
and users/DBA

A

Active data dictionary

32
Q

is accessed by users/DBA only

A

Passive data dictionary

33
Q

Combines everything into single system including- DBMS software, hardware, application programs, and user interface processing software

A

Centralized DBMS

34
Q

Provide appropriate interfaces through a client software module to access and utilize the various server resources

A

Clients

35
Q

Provides database query and transaction
services to the clients

A

DBMS Server

DBMS (10 decks)

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