chapter 1-introduction to database system
DESCRIPTION
CHAPTER_1-INTRODUCTION_TO_DATABASE_SYSTEMPoliteknik Melimau MelakaEC601 Database System Chapter 1TRANSCRIPT
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Database System EC601
MRS. ISMA SHAMSURIA BINTI ISMAIL
Department of Electrical Engineering (LEVEL 1)The Polytechnic of Merlimau, Melaka
019-4211728 ext:1163
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DATABASE SYSTEM course offers a comprehensive
coverage of basic concept and application of data
manipulation. Student will learn the fundamental
concepts and techniques for designing and developing
database and manipulating data using Structured Query
Language (SQL).
Course Outline
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NOCOURSE LEARNING OUTCOMES
(CLO)PLO
LEARNING
DOMAINS
1 Explain the basic concepts of database model using entity-relationship diagram and translating completed data models by applying normalization technique in logical database designs.
PLO 1
PLO 2
PLO 9
C4
2
Apply Structured Query Language (SQL) for database manipulation using a database management system in practical works inclusive of a report within stipulated time frame.
P4
3
Demonstrate problem solving skill in developing new database applications based on an assigned problem.
A3
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CLO Types Of Assessment
Percentage
(%)
1. CONTINUOUS
ASSESSMENT (CA) 50
CLO1 i. Quiz (minimum 4) 20 CLO1 i. Theory Test (minimum 1) 20 CLO1, CLO2, CLO3
i. Practical Work (minimum 6)
50
CLO3i. Presentation (minimum
1)10
1. FINAL EXAMINATION (FE) 50Total 100
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Introduction ToDatabase System
CHAPTER ONE
CLO 1 : Explain the basic concepts of database
model using entity-relationship diagram and
translating completed data models by applying
normalization technique in logical database
designs.
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DATA are raw facts used to indicate that the facts have not yet been
processes.
- Data can be recorded and that have implicit meaning. For
example, consider the names, telephone numbers, and
addresses of the students.
INFORMATION is produced by processing data used to reveal the
meaning of data.
- For example, student information record including the names, telephone
numbers, and addresses of the students.
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DATABASE
– A collection of data stored in a standardized format,
designed to be shared by multiple users.
DATABASE MANAGEMENT SYSTEM (DBMS)
– Software that defines a database, stores the data,
supports a query language, produces reports, and
creates data entry screens.
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A DATABASE has some source from which data is derived,
some degree of interaction with events in the real world, and
an audience that is actively interested in its contents.
The end users of a database may perform business
transactions (for example, a students pays a fee) or events
may happen (for example, a polytechnic has a student) that
cause the information in the database to change.
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No Level Description
1. Character basic logical data element. It consists of a single alphabetic, numeric, or other symbol.
2. Field It consists of a grouping of characters. A data field represents an attribute (a characteristic or quality) of some entity (object, person, place, or event).
3. Record A group of the related fields of data Represents a collection of attributes that describe an entity.
4. File A group of related records Frequently classified by the application for which they are primarily used Also classified by their permanence, for example, a master file versus a transaction file.
5. Database An integrated collection of logically related records or objects. A database consolidates records previously stored in separate f files into a common pool of data records that provides data for many applications.
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Uncontrolled Duplication Wastes space Hard to update all files
Inconsistent data Inflexibility
Hard to change data Hard to change programs
Limited data sharingPoor enforcement of standardsPoor programmer productivityExcessive program maintenance
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Database Management System (DBMS)
File-based System
Database System
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1. DBMS - a computer software program that enables users to
access, create and maintain a database.
2. DBMS is also the combination of data, hardware, software
and users to help an enterprise manage its operational data.
3. The main function of a DBMS - to provide efficient and
reliable methods of data retrieval to many users.
4. The general-purpose of DBMS - facilitates the processes of
defining, constructing, manipulating, and sharing databases
among various users and applications.
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No Process Description
1. Defining specifying the data types, structures, and constraints of the
data to be stored in the database.
Data files - files that store the database information
Meta-data - such as index files and data dictionaries, store
administrative information.
2. Constructingprocess of storing the data on some storage medium that is
controlled by the DBMS.
3. Manipulating functions such as querying the database to retrieve specific
data, updating the database to reflect changes in the
miniworld, and generating reports from the data.
4. Sharingallows multiple users and programs to access the database
simultaneously.
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Advantages of Database Approach
Minimal data redundancy.
Data consistency.
Integration of data.
Sharing of data.
Enforcement of standards.
Ease of application development.
Uniform security, privacy and integrity.
Data independence.
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Data is most important Data defined first Standard format
Access through DBMS Queries, Reports, Forms Application Programs 3GL Interface
Data independence Change data definition without
changing code Alter code without changing data Move/split data without changing
code16
All Data
DBMS
Program1 Program2QueriesReports
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Oracle
Ingres
Informix (Unix)
DB2, SQL/DS (IBM)
Access (Microsoft)
SQL Server (Microsoft +)
Many older (Focus, IMS, ...)
Many limited PC (dBASE, Paradox, …)
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A file based system - a collection of application
programs that perform services for the end-users, usually
the production of reports.
Each program within a file based system defines and
manages its own data - there are limits as to how that
data can be used or transported.
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Were developed as better alternatives to paper based
filing systems.
Files stored on computers - the data could be accessed
more efficiently.
Common practice for larger companies - each of its
departments looking after its own data.
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The PROBLEMS of file based system are:
Data separation and isolation
Data dependence
Data duplication
Incompatible data (different file formats)
Lack of flexibility in organizing and querying the data
Increased number of different application programs
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Database system is a system to achieve an organized,
store a large number of dynamical associated data, facilitate
for multi-user accessing to computer hardware, software
and data, that it is a computer system with database
technology.
The database approach emerged to resolve the problems
with the file-based approach.
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Sharing of data
Consistency of data
Integrity of data
Security of data
Data independence
Allows for more analysis of
the same amount of data
Advantages of database systems are:
Improved data access and
system performance
Potentially increased
productivity
Increased concurrency
Improved data backups and
recovery
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The main characteristics of the database approach versus the file processing approach are the following:
1. Self-describing nature of a database system
2. Insulation between programs and data, and data
abstraction
3. Support of multiple views of the data
4. Sharing of data and multiuser transaction processing
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Database System contains not only the database itself
but also the descriptions of data structure and
constraints (meta-data) - used by the DBMS software or
database users if needed.
This separation makes database system totally different
from traditional file-based system in which data
definition is a part of application programs.
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2. Insulation between Program and Data
In the filed base system, the structure of the data files is
defined in the application programs so if user want to
change the structure of a file, all the programs access to
that files might need to be changed.
In database approach, data structure is stored in the
system catalog not in the programs so such changes
might not occurs.
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3. Support multiple views of data
A view is a subset of the database which is defined
and dedicated for particular users of the system.
Multiple users in the system might have different views
of the system.
Each view might contains only the interested data of
an user or a group of user.
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4. Sharing of data and Multiuser system
A multiuser database system must allow multiple
users access the database at the same time.
As the result, the multiuser DBMS must have
concurrency control strategies to ensure that several
user try to access the same data item at a time do
so in the manner so that the data always be correct.
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Airlines and railwaysBankingTelecommunicationsEducation
Credit card transactionsE-commerceHealth care information
systems and electronic patient record
Digital libraries and digital publishing
FinanceSalesHuman resources
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1. PERSONAL DATABASE
Also known as a SINGLE USER Database / a
DESKTOP Database
Supports only one user at a time
User B or C must wait until user A has completed his
database work.
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2. WORKGROUP DATABASE
Also known as a MULTIUSER Database
Supports a relatively small number of users (<50)
A specific department within an organization using the
same database – DEPARTMENT DATABASE
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3. ENTERPRISE DATABASE
The database used by the entire organization
Supports MANY users (>50) across many departments
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The DBMS acts as an interface between what two
components of an enterprise-class database
system?
A. Database application and the database
B. Data and the database
C. The user and the database application
D. Database application and SQL
A
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The following are components of a database
except ________ .
A. user data
B. metadata
C. reports
D. indexes
C
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An application where only one user accesses the
database at a given time is an example of a
________ .
A. single-user database application
B. multiuser database application
C. e-commerce database application
D. data mining database application
A
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An on-line commercial site such as Amazon.com is
an example of a ________ .
A. single-user database application
B. multiuser database application
C. e-commerce database application
D. data mining database application
C
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Metadata enables database designers and users to
do all of the following except:
A. sample data.
B. understand what data exist.
C. what the fine distinctions are between similar data
items.
D. what the data mean.
A
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A database management system (DBMS) is a:
A. hardware system used to create, maintain, and provide controlled
access to a database.
B. hardware system used to create, maintain, and provide uncontrolled
access to a database.
C. software system used to create, maintain, and provide controlled
access to a database.
D. software system used to create, maintain, and provide uncontrolled
access to a database.
C
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Because it contains a description of its own structure, a
database is considered to be ________ .
A. described
B. metadata compatible
C. self-describing
D. an application program
C
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The following are functions of a DBMS except
________ .
A. creating and processing forms
B. creating databases
C. processing data
D. administrating databases
A
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Structured data may include which of the following?
A. Photo image
B. Video clip
C. Dates
D. None of the above.
C
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Helping people keep track of things is the purpose of a(n)
________ .
A. database
B. table
C. instance
D. relationship
A
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Some advantages of the database approach include all, but:
A. minimal data redundancy.
B. improved data consistency.
C. improved data sharing.
D. program-data dependency.
D
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An Enterprise Resource Planning application is an example of
A ________ .
A. single-user database application
B. multiuser database application
C. e-commerce database application
D. data mining database application
B
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1. In a database, data is stored in spreadsheets which have rows and columns.
2. A database has data and relationships.
3. In an enterprise-class database system, business users interact directly with database applications, which directly access the database data.
4. Applications are programs that interact directly with the database.
5. A database has a built-in capability to create, process and administer itself.
6. A database design may be based on existing data.
7. A workgroup typically comprises between 25 and 100 persons.
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MODEL
A Model is representation of reality, ’real world’ objects and
events and their associations.
A database model is an organizing principle that specifies
particular mechanism of data storage and retrieval.
The model explains, in terms of services available to an
interfacing application, how to access a data element when
other related elements are known.
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Data Model is a collection of concepts that can be used to describe the structure of database.
Structure of database means data types, relationships and constraints.
In addition, most data model include a set of basic operations for specifying retrievals and modifications on the database.
Data Model provides a means to achieve Data Abstraction. Data Abstraction is refers to the hiding of certain details of
how the data are stored and maintained. With several levels of abstraction, the user’s view of the database is simplified and this leads to the improved understanding of data.
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The major purpose of a database system is to provide users with an abstract view of the system.
Complexity should be hidden from database users. There are 3 levels of abstraction:
Levels of Abstraction
Description
Physical level how the data is stored physically and where it is stored in database.
Logical level what information or data is stored in the database (like what is the data type or what is format of data)
View level end users work on view level. if any amendment is made it can be saved by other name.
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• Views describe how users see the data.
• Conceptual schema defines logical structure
• Physical schema describes the files and indexes used.
Physical Schema
Conceptual Schema
View 1 View 2 View 3
DB
Users
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Purpose of Data Model
To represent data.
To make the data understandable.
Types of Data Models
1. Object Based Data Models
2. Physical Data Models
3. Record Based Logical Data Models
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1. Object Based Data Models
It use concepts such as entities, attributes and
relationships.
Types of Object Based Data Models:
Entity Relationship (ER)
Object Oriented
Semantic
Functional
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a. The Entity Relationship (ER) Model
Based on a perception of the world as consisting of a collection of basic objects (entities) and relationships among these objects. An entity is a distinguishable object that exists. Each entity has associated with it a set of attributes
describing it. A relationship is an association among several entities. The set of all entities or relationships of the same type is
called the entity set or relationship set. Another essential element of the E-R diagram is the mapping
cardinalities, which express the number of entities to which another entity can be associated via a relationship set.
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Database System Design
User viewsof data.
Conceptualdata model.
Customer(CustomerID, Name, Address, …)
SalesPerson(EmployeeID, Name, Commission, … )
Order(OrderID, OrderDate, CustomerID, EmployeeID, … )
OrderItem(OrderID, ItemID, Quantity, Price, … )
Item(ItemID, Description, ListPrice, …)
Implementation(relational)data model.
Physicaldatastorage.
Class diagram that shows business entities, relationships, and rules.
List of nicely-behaved tables. Use data normalization to derive the list.
Indexes and storage methods to improve performance.
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The Entity Relationship (ER) Model sample diagram
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b. The Object-Oriented Model
Based on a collection of objects - class, like the E-R model. An object contains values stored in instance variables
within the object. Unlike the record-oriented models, these values are
themselves objects. Thus objects contain objects to an arbitrarily deep level of
nesting. An object also contains bodies of code that operate on
the object. These bodies of code are called methods.
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61
CustomerCustomerIDName… Add CustomerDrop CustomerChange Address
OrderOrderIDCustomerID… NewOrderDeleteOrder…
OrderItemOrderIDItemID… OrderItemDropOrderItem…
ItemItemIDDescription… New ItemSell ItemBuy Item …
GovernmentCustomer
ContactNameContactPhoneDiscount, …
NewContact
CommercialCustomer
ContactNameContactPhone…
NewContact
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c. Semantic
ABSTRACTIONS:
• CLASSIFICATION
• AGGREGATION
• GENERALIZATION
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d. FunctionalProvides an unified approach to manipulation both data and procedures. Main idea - is a definition of all components of an information system in the form of functions. Example: defines data objects, attributes and relationships as so-called database functions. A Functional Data Manipulation Language is a number of data manipulation functions which can be applied to database functions. Users are provided with a special mechanism which is called Lambda Calculus to define their own functions which can be seamlessly combined with database and data manipulation functions mentioned above.
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Functional Data model Diagram
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2. Physical Data Models
It describe how data is stored in the computer, representing
information such as record structures, record ordering and access
paths.
Less no. of models are there.
Are used to describe data at the lowest level.
Very few models, e.g.
Unifying model.
Frame memory.
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3. Record Based Logical Data Models
Used to specify the overall logical structure of the database. The database consists of a no. of fixed formats of different types. Each record type defines a fixed no. of fields having a fixed length.
3 types of record based data model:
a. Hierarchical data model.
b. Network data model.
c. Relational data model.
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a. The Hierarchical Model
Similar to the network model.
Organization of the records is as a collection of trees,
rather than arbitrary graphs.
The relational model does not use pointers or links, but
relates records by the values they contain. This allows a
formal mathematical foundation to be defined.
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Customers
Orders
Item Description Quantity998 Dog Food 12764 Cat Food 11
Items
Customer
Order
Items Ordered
To retrieve data, you must start at the top (customer). When you retrieve a customer, you retrieve all nested data.
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b. The Network Model
Data are represented by collections of records.
Relationships among data are represented by links.
Organization is that of an arbitrary graph.
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Customer
OrderItems
Ordered
Items
Entry point
Entry point
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c. The Relational Model
Data and relationships are represented by a collection of
tables.
Each table has a number of columns with unique names,
e.g. customer, account.
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Customer(CustomerID, Name, …
Order(OrderID, CustomerID, OrderDate, …
ItemsOrdered(OrderID, ItemID, Quantity, …
Items(ItemID, Description, Price, …
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Schema
Logical structure of database.
The description of the database which is designed in the
early stage and is not expected to change frequently.
Database system have several schemas.
Example:
Book (Bid: char(2), Title: char(50), Author:char(20),
Price: decimal(5,2))
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Instance
Actual content of database at particular moment.
Since information can be inserted to or deleted from
database at anytime, database changes over time.
Example:Bid Title Author Price
11 Franklin forgets Bourgeois 7.00
22 Arthur and the Seventh-Inning Stretcher Krensky 14.00
33 Midnight Wrestlers Morgan 11.00
44 Midnight Pilot Morgan 9.00
55 Book of Science Activities 18.00
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DATA DEFINITION LANGUAGE (DDL)
Specification notation for defining the database schema
DDL compiler generates a set of tables stored in a data
dictionary – meta data (data about data)
Data storage and definition language – special type of
DDL in which the storage structure and access method
used by the database system are specified
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CREATE DATABASE - Creates a new database
ALTER DATABASE - Modifies the database
DROP DATABASE - Drops (deletes) a database
CREATE TABLE - Creates a new table
ALTER TABLE - Modifies the table
DROP TABLE - Drops (deletes) a table
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DATA MANIPULATION LANGUAGE (DML)
Language for accessing and manipulating the data organized
by appropriate data model
2 classes of language :
Procedural – user specifies what data required and how to get
those data
Nonprocedural – user specifies what data required without
specifying how to get those data
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SELECT - Retrieves data from the database
INSERT - Inserts new data into the database
UPDATE - Updates existing data in the database
DELETE - Deletes existing data from the database
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4G LANGUAGE (4GL)
Fourth-generation programming language (1970s-1990)
A very high level programming language and a development
environment or 'Analyst Workbench' designed with a central
data dictionary system, a library of loosely coupled design
patterns, a CRUD generator, report generator, end-user query
language, DBMS, visual design tool and integration API.
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4G LANGUAGE (4GL)
4GL is more oriented toward problem solving and systems
engineering.
Not always successful in this task, sometimes resulting in
inelegant and unmaintainable code. However, given the right
problem, the use of an appropriate 4GL can be spectacularly
successful.
Are designed to reduce programming effort, the time it takes
to develop software, and the cost of software development
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1. HARDWARE
All system’s physical devices
Main component – computer and computer peripherals
Networks
DBMS COMPONENT MODULES
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2. SOFTWARE
OS software - Manages all hardware components
DBMS software – Manages the database within the
database system
Application programs and utility software – access and
manipulate data in DBMS
DBMS COMPONENT MODULES
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3. USERS/PEOPLEapplication programmers, non-computer science expert and
experienced user, database designers, system administrators
4. PROCEDURES Instructions and rules that govern the design and use of
database systemUsed to ensure that there is an organized way to monitor and
audit both data enter and information that is generated
5. DATACollection of facts stored in database
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DBMS COMPONENT MODULES
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Which of the following database activities determines the
entities, attributes, and relationships of data?
A. Conceptual data modeling
B. Logical database design
C. Physical database design and definition
D. Database implementation
A
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An entity type is which of the following?
A. A major category of data about people, place, and things
B. The various departments of an organization
C. The application software
D. The business processes the support the mission of an
organization
A
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Which of the following database activities require a specific
knowledge of a DBMS?
A. Enterprise modeling
B. Conceptual data modeling
C. Logical database design
D. Physical database design and definition
D
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User views are included as part of which schema?
A. Internal
B. Conceptual
C. External
D. None of the above.
C