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