Fundamentals of Database Systems: Chapter 1, 2, and 3

System Analysts

Application designers whose designs to meet the requirements of naive and sophisticated users

True

Attribute names are enclosed in overalls and are attached to their entity type by straight lines

Transaction

Causes some data to be read and some data to be written into the database

DML

DML = Data Manipulation Language It is used to insert, retrieve, update, and delete the records in the database

Key attribute

One or more attributes whose values are distinct for each individual entity in the entity set. It's values can be used to identify each entity uniquely.

Business Analysts

People who can analyze vast amounts of business data and real time data, big data, for better decision making related to planning, advertising, marketing, etc.

True

Relationships can generally be of any degree, but the ones most common are binary relationships

Catalog

Stores the description of a particular database

Physical design

The last step or phase of database design, During which the internal storage structures, file organizations, indexes, excess paths, and physical design parameters for the database files are specified. In parallel with these activities, application programs are designed and implemented as database transactions corresponding to the high-level transaction specifications

Degree of a relationship type

The number of participating entity types

Attributes

The particular prop properties that describe an entity. For example an employee entity may be described by the employers name, age, address, etc.

Constructing

The process of storing the data on a storage medium that is controlled by the DBMS

Data requirements

The result of this step is a concisely written set of users requirements. These requirements should be specified in as detailed and complete a form as possible.

Conceptual design Space --> conceptual schema

The second step or phase of database design

Logical design, or data model mapping

The third step or phase of database design, it results in a database schema in the implementation data model of the DBMS

True

The value of a composite attribute is the concatenation of the values of its component simple attributes

Operators and Maintenance Personnel

They manage the actual running and maintenance of the database system hardware and software environment.

What are the three main categories of a data model?

1) high-level or conceptual data models 2) low-level or physical data models 3) representational or implementation data models

Database Scheme

A basic structure to define how the data is organized in the database (describes the overall design of the database)

Database

A collection of related data

Database Management System (DBMS)

A computerized system that enables users to create and maintain a database

Client/Server Architecture

A database architecture that contains two modules: 1) A client module (usually a pc) that providers the user interface 2) A server module that can response to the user queries and provides services to the clients machines

Online Transaction Processing (OLTP)

A major part of database applications allowing hundreds of concurrent transactions to execute per second

True

A multi valued attribute may have lower and upper bounds to constrain the number of values allowed for each individual entity.

Ternary relationship type

A relationship type of degree three we are each relationship instance associates three entities

Binary relationship type

A relationship type of degree two we are each relationship instance associates two entities

Maintenance

A system's evolution as requirements change over time

Casual End-User

Accesses database occasionally when needed

Application Program

Accesses the database by sending queries and requests for data to the DBMS

Program-Data Independence

Allows changing data structures and storage organization without having to change the DBMS access programs

Sharing

Allows multiple users and programs to access the database simultaneously

Universe of Discourse (UoD)

An aspect of the real world a database represents, also known as miniworld

Schema or intension

An entity type for a set of entities that share the same structure.

Derived attribute

And attribute that can be derived from a stored attribute

Multi valued attribute

And attribute that has a set of values for the same entity, four example, colors of a car

TRUE

And entity type is represented in ER diagrams as a rectangular box and closing the entity type name

Simple attribute/atomic attribute

Attributes that are not divisible

Composite attributes

Attributes that can be divided into smaller subparts, which represent more basic attributes with independent meanings. Composite attributes can form a hierarchy; for example, street address can be further subdivided into three simple component attributes: number, Street, and apartment number.

Single - valued attributes

Attributes that have a single value for a particular entity. For example, age is a single valued at your view of a person.

True

Composite attributes are attached to their component attributes by straight lines

Functional requirements

Consist of the user defined operations or transactions that will be applied to the database, including both retrievals and updates.

n-tier architecture

Consists of four or five layers. The intermediate layer or business logic layer is divided into multiple layers.

Three-tier architecture

Consists of three layers: client, application server, and database server The client machine usually contains the user interface and the intermediate layer (application layer) running the application programs and storing business rules. The database layer stores the data.

DDL

DDL = Data Definition Language It is used to create, alter, and drop the database tables, views, and indexes.

What is the difference between a database schema and a database state?

Database Schema - Description of the Database Data State - is the database at a particular moment in time

Entity type/Entity set

Defines a collection (or set) of entities that have the same attributes.

Relationship type/Relationship set

Defines a set of associations among entities from entity types

External Schema (User Level Schema)

Describes the data which is viewed by the end users. Describes the part of the database for a user group and it hides the rest of the database from that user group.

Data Model

Describes the logical structure of the database and it introduces abstraction in the DBMS. Provides a tool to describe the data and their relationships.

Conceptual Schema (Logical Level Schema)

Describes the logical structure of the whole database for a group of specific users. It hides the internal details of the physical storage structure.

System Designers and Implementors

Design and implement DBMS packages in the form of modules and interfaces and test and debug them. The DBMS must interface with applications, language compilers, operating system components, etc.

Tool Developers

Design and implement software systems called tools for modeling and designing databases, performance monitoring, prototyping, test data generation, user interface creation, simulation etc. that facilitate building of applications and allow using database effectively.

Not Only SQL (NOSQL)

Designed for rapid search and retrieval from documents, processing of huge graphs occurring on social networks, and other forms of unstructured data with flexible models of transaction processing

Recovery Subsystem

Ensures each completed transaction has its effect permanently recorded in the database

Manipulation

Functions such as querying the database to retrieve specific data, updating the database to reflect changes in the miniworld, and gathering reports from the data

Concurrency Control

Guarantees that each transaction is correctly executed or aborted

Query Language

High-level language used to retrieve data from the database

Application Programmers

Implement the specifications developed by analysts and test and debug them before deployment

True

In ER diagrammatic notation, each key attribute has its name underlined inside the oval

Protection

Includes system protection against hardware or software malfunction and security protection against unauthorized or malicious access

Data

Known facts that can be recorded and that have implicit meaning

What is the difference between logical data independence and physical data independence? Which one is harder to achieve?

Logical data independence is the capacity to change the conceptual schema without changing the external schema. Physical data Independence is the capacity to change the internal schema without changing the conceptual or external schema. Logical data independence is harder to achieve because changing attribute constraints and the structure of tables can result in invalid data for the changed attributes.

Stand-Alone End-Users

Mostly maintain personal databases using ready-to-use packaged applications

True

Multi valued attributes are displayed in double ovals

Standards

Names, display formats, screens, report structures, meta-data, web page layouts, etc. of data items

Sophisticated End-Users

Professionals thoroughly familiar with the system capabilities

Complex attributes

Represents arbitrary nesting by grouping components of a composite attribute between parentheses () and separating the components with commas, and by displaying multivalued attributes between braces {}

Internal Schema (Physical level schema)

Represents the structure of the data as viewed by the DBMS and describes the physical storage structure of the database.

Database Administrators

Responsible for authorizing access to the database, coordinating and monitoring its use, acquiring software and hardware resources, controlling its use, and monitoring efficiency of operations

Database Designers

Responsible to define the content, the structure, the constraints, functions or transactions against the database, and communicating with end-users and understanding their needs

SDL

SDL = Storage Definition Language It is used to specify the internal schema of the database and specify the mapping between two schemas

ER diagrams

Shows how the schema for a database application can be displayed by means of a graphical notation

Role name

Signifies the role that a participating entity from the entity type plays in a relationship instance, and it helps to explain what the relationship

Cardinality ratio for binary relationships

Specifies the maximum number of relationship instances that an entity can participate in. A carnality ratio X and Y of 1:N means that each X can be related to any number of Y and Y can be related to at most one X

True

Superfluous attributes must not be included in a key

Queries

The accessing of different parts of data and formulating the result of a request

Database State

The actual stored data in the database in a particular moment in time

Entity

The basic concept that and ER model represents, it is a thing or object in the real world with an independent existence. each entity has attributes that particular properties that describe it.

Data Independence

The capacity to change the scheme at the physical level of a database system without affecting the schema at the conceptual or external level.

Entity collection/entity set

The collection of all entities of a particular entity type in the database at any point in time

True or false?

The concepts in a conceptual design do not include implementation details.

Data Sublanguage

The data manipulation language commands are embedded in a general-purpose language to manipulate the data such as insert, update, delete, etc operations in the database.

Database System

The database and DBMS software together

Meta-Data

The database definition or descriptive information stored by the DBMS in the form of a database catalog or dictionary

Requirements collection and analysis --> data requirements

The first step or phase of database design

Describe the three-schema architecture. Why do we need mappings among schema levels?

The three-schema architecture separates the user applications and the physical database. It has three levels: 1) Internal Level - physical storage structure of the database 2) Conceptual level - the structure of the whole database for a community of users. Mapping defines the correspondence between the conceptual view and the shared database. 3) External level - the part of the database that a particular user group is interested in and hides the rest of the database from that group. Mapping defines the relationship between the external view and the conceptual view.

Conceptual

This approach enables database designers to concentrate on specifying the properties of the data, without being concerned with storage and implementation details, which makes it easier to create a good conceptual database design.

Functional requirements

This step or phase runs parallel with the first step or phase of database design- requirements collection and analysis

Naïve/Parametric End-User

Those who use previously well-defined functions in the form of "canned transactions" against the database

End-Users

Use the data for queries, reports, and updating of database content

Host Language

Used for application programming in a database. The DML commands are embedded in a general-purpose language to manipulate the data in the database.

Data Abstraction

Used to hide storage details and present the users with a conceptual view of the database

NULL

Used to indicate an attribute is not applicable, or the attribute is unknown

Conceptual schema

Using a high-level conceptual data model, it includes detailed descriptions of the entity types, relationships, and constraints;

VDL

VDL = View Definition Language It specifies the user views and their mappings to the logical schema in the database.

True

Value sets are not typically displayed in basic ER diagrams

Extension of the entity type

When the collection of entities of a particular entity type is grouped into an entity set

Recursive relationships/self referencing

When the same entity type participates more than once in a relationship type in different roles. In such cases the role becomes essential for distinguishing the meaning of the role that each participating entity plays

Database Utility

a software module to help the DBA manage the database

A value set/ domain

the set of values that may be assigned to that attribute for each individual entity