Database Management Systems Defined

What are some characteristics of the Database Approach?

- A central repository of shared data - Data is managed by a controlling agent - Data is stored in a standardized, convenient format - you need a Database Management System to use this approach

Components of the database environment

- Data modeling and design tools - A repository - Database management System - Database - Application programs - User interface - Data and Database administrators - System developers - End users

Improved data quality is helped by the Database approach in what way?

- Database designers can specify integrity constraints that are enforced by the DBMS - It can help clean data and remove duplicates

What are some of the problems with data dependency?

- Each application programmer must maintain their own data - Each application program needs to included code for the metadata of each file - Each application program must have its own processing routines for reading, inserting, updating, and deleting data - Lack of coordination and central control - File formats arent standardized

Some key characteristics of the Enterprise Data Model

- Specifies the scope and general content - gives an overall picture of organizational data at a high level - Includes an Entity-relationship diagram - Describes the entity types - Shows the relationships between entities - Tells you the Business rules

Repository - what it is and what it is connected to in the database environment

- a centralized knowledge base for all data definitions, data relationships, screen and report formats, and other system components (i.e. where the metadata resides) - It is connected to the *DBMS* and the *Data modeling and design tools*

Database Management System (DBMS) - what it is and what it is connected to in the database environment

- a software system that is used to create, maintain, and provide controlled access to databases - It is connected to the *Repository*, *User Interface*, *Application programs*, and the *Database*

Database - what it is and what it is connected to in the database environment

- an organized collection of logically related data, usually designed to meet the information needs of multiple users in an organization - It is connected to the *DBMS*

Data modeling and design tools - what they are and what they are connected to in the database environment

- automated tools used to design databases and application programs. These tools help with creation of data models and in some cases can also help automatically generate the "code" needed to create the database. - They are connected to the *User Interface* and *Repository*

Internal Schema

- consists of two data schemas: a logical schema and a physical schema - The underlying design and implementation

User Interface- what it is and what it is connected to in the database environment

- includes languages, menus, and other facilities by which users interact with various system components (i.e. what the user sees, not the back end stuff) - it is connected to the *Data modeling and design tools*, *repository*, *Database management System*, *Application programs*, *User interface*, *Data and Database administrators*, *System developers*, and *End users*

The 3 reasons why database applications can often be developed much more rapidly than conventional file applications

- the application developer can concentrate on the specific functions required for the new application, without having to worry about file design or low-level implementation details - provides a number of high-level productivity tools that automate some of the activities of database design and implementation - Web services help improve application developers' productivity

System developers - what it is and what it is connected to in the database environment

- the people responsible for designing databases and who create the application programs/software - Connected to the *User Interface*

End Users - what it is and what it is connected to in the database environment

- the people who use the systems for various business functions; can include accountants, sales people, managers, etc. - Connected to the *User Interface*

Application programs - what they are and what it is connected to in the database environment

- they interact with the database to provide functionality of use for the company and fulfill the order processing, invoicing, and payroll functions. I.e. the software using the data - It is connected to the *User interface* and the *DBMS*

Database administrators (and the data) - what it is and what it is connected to in the database environment

- they manage/maintain the data and database - Connected to the *User Interface*

How is a database different from a repository?

A database contains data, while a repository contains metadata/defines the structure of the data

"one order involves many products and one product is involved in many orders" is an example of what?

A many to many relationship

Project

A planned undertaking of related activities to reach an objective that has a beginning and an end.

Rapid Application (RAD) Approaches

Agile, eXtreme programming, Scrum, DSDM Consortium, Feature-driven development

Why Program-Data Dependence is a disadvantage of File Processing

All programs contain their own unique metadata for each file they use, so the way an organization's data is structure may be dependent on the program they are using

Prototyping

An iterative process of systems development in which requirements are converted to a working system that is continually revised through close work between analysts and users.

A Database is...

An organized collection of logically related data

A database is...

An organized collection of logically related data. It can be any size and have any level of complexity

People involved when managing projects

Business analysts Systems analysts Database analysts and data modelers Users Programmers Database architects Data administrators Project managers Other technical experts

Improved decision support

Certain databases are design solely to help make decisions in a specific area of the business (supply chain, finance, customer relationships, etc.)

If your prototype is inefficient, you should...

Convert to a prototype (i.e. tune the database for improve performance and fix errors in the database)

Examples of databases

Customer contacts, Transnational data (sales, deliveries, invoices), a Data warehouse

The biggest problem with data redundancy is...

Data changes in one file could cause inconsistencies and thus compromises data integrity

Elements of the Database Approach

Data models, Entities, Relationships, Relational Databases

What are the 2 types of data models?

Enterprise Data Models and Project Data Models

The Database Schema consists of...

External Schema, Conceptual Schema, and Internal Schema

What are Data Models?

Graphical diagrams capturing the nature and relationships of data

installation and management cost and complexity as a risk of the database approach

High fixed cost to set up the database, and many high variable costs are required to keep it running smoothly

The Prototyping Database Methodology

Identify the problem ==> Develop the initial prototype ==>Implement and use the prototype ==> Revise and enhance the protoype

Reduced program maintenance

In a database environment, data are more independent of the application programs that use them. Within limits, we can change either the data or the application programs that use the data without necessitating a change in the other factor.

Why Duplication of Data is a disadvantage of File Processing

It is not good when different systems/programs have separate copies of the same data because it requires additional storage space and increased effort to keep all files up to date

If a word inside an entity is underlined (when looking at an ER diagram) what does this mean?

It is the primary key

Costs of converting to the database approach are typically higher for _____________ companies.

Larger

NICNO - acronym to help remember the costs and risks of the database approach

N ew, specialized personnel I nstallation and management cost and complexity C onversion costs N eed for explicit backup and recovery O rganizational conflict

Costs and Risks of the Database Approach

New, specialized personnel Installation and management cost and complexity Conversion costs Need for explicit backup and recovery Organizational conflict

"One customer may place many order, but each order is placed by a single customer" is an example of what?

One to many relationship

"One order has many order lines; each order line is associated with a single order" is an example of what?

One to many relationship

PELLFD - Acronym to remember all the disadvantages of File Processing

P rogram-data dependence E xcessive program maintenance L imited data sharing L engthy development times F iles available for anyone to edit D uplication of data

Steps of SDLC and the data models used during each stage

Planning (Enterprise Data model) ==> Analysis (External Schema/User View, Conceptual Schema) ==> Logical Design (Logical Schema, External Schema/User View) ==> Physical Design (Physical Schema) ==> Implementation ==> Maintenance

What are this disadvantages of File Processing?

Program-Data Dependence, Duplication of Data, Limited Data Sharing, Lengthy Development Times, Excessive Program Maintenance, Files are available for anyone to edit/alter

Advantages of the Database Approach

Program-data independence Planned data redundancy Improved data consistency Improved data sharing Increased application development productivity Enforcement of standards Improved data quality Improved data accessibility and responsiveness Reduced program maintenance Improved decision support

What does the data repository help with?

Providing database administrators with a powerful set of tools for developing and enforcing database standards

Improved data accessibility and responsiveness

SQL can be used to extract data very easily

The two approaches to Database and IS Development

System Development Life Cycle (SDLC) and Prototyping

What is an attribute?

The data you are interested in capturing about the entity (ex: customer name). They are included inside of entity boxe

What is the solution to all the flaws of traditional file processing?

The database approach

Need for explicit backup and recovery as a risk of the database approach

The database must be backed up in case of damage and this is costly

What does it mean for an entity (box) to have curved edges in an E-R diagram?

The entity is an associative entity

Enterprise Data Model

The first step in database development, in which the scope and general contents of organizational databases are specified.

What is an instance?

The information collected for each entry in the database

Function to Data Entity Matrix

The matrix matches business functions with the data entity types they need

Improved data consistency

The result of reduced data redundancy, helps avoid wasted storage space

System Development Life Cycle (SDLC)

The traditional methodology used to develop, maintain, and replace information systems. Detailed and well planned out; time consuming but comprehensive; *Long* development cycle. AKA Waterfall approach

Why Limited Data Sharing is a disadvantage of File Processing

There is no centralized control of the data that can easily share the data with who needs it and it is difficult to share the data outside of the program it is contained in; silo effect can develop because of this

Database analysts and data modelers

These individuals concentrate on determining the requirements and design for the database component of the information system.

What are Relationships?

They are associations between entities that exist in organizational data so that desired information can be retrieved

What came before database systems? What is an example of this?

Traditional file systems; Excel

External Schema

Typically involves users (managers and other employees) the most; can be represented as a combination of the enterprise data model (a top-down view) and a collection of detailed (or bottom-up) user views

Improved data sharing

When the database approach makes it easier to deploy and control data access

Crows feet in an ER Diagram represent what?

a "many" relationship

Traditional File Processing (TFS) is...

a computer application that stores and arranges information in a file (i.e. an excel spreadsheet)

What is a user view?

a logical description of some portion of the database that is required by a user to perform some task. A user view is often developed by identifying a form or report that the user needs on a regular basis

What are entities

a noun in that it describes a person, a place, an object, an event, or a concept in the business environment for which information must be recorded and retained. Examples include customers and orders

What is a constraint?

a rule that can't be violated by database users

Database Management System definition

a software system that enables the use of a database and provides a systematic method to create, update, store and retrieve data from the database

Program-data independence

allows an organization's data to change and evolve without changing the application programs that process the data

Agile Development

an approach to database and software development that emphasizes: Individuals and interactions over processes and tools Working software over comprehensive documentation Customer collaboration over contract negotiation, and Responding to change over following a plan

What is an associative entity?

an entity that represents the association between two other entities; it can be thought of as a combination entity/relationship

Why Excessive Program Maintenance is a disadvantage of File Processing

as much as 80 percent of the total information system's development budget might be devoted to program maintenance, meaning that resources aren't being spent on developing new applications

Conceptual Schema

combines the different external views into a single, coherent, and comprehensive definition of the enterprise's data. The conceptual schema represents the view of the data architect or data administrator

Organizational conflict as a risk of the database approach

conflicts on data definitions, data formats and coding, rights to update shared data, and associated issues are frequent and often difficult to resolve

As businesses become more complex, they run up against the limitations of their ____________________________.

data storage methods

Physical Schema

describes how data are to be represented and stored in secondary storage using a particular DBMS; involves the database administrator

Programmers

design and write computer programs that have commands to maintain and access data in the database embedded in them.

Why Length Development Times are a disadvantage of File Processing

each new application requires that the developer essentially start from scratch by designing new file formats and descriptions and then writing the file access logic for each new program

The term "data integrity" refers to __________________________________________________________.

ensuring the validity, security, and availability of a company's data

Access to the data is controlled and managed by ___________.

experts

What is the most common source of database failures in organizations?

failure to implement a strong database administration function

Planned data redundancy

helps integrate files into a logical structure and helps improve database performance

What are Enterprise Data models?

high-level entities and relationships for the organization represented in graphical form; helps you understand the scope of the business and how different parts of the business are connected

Systems analysts

may perform business analyst activities but also specify computer systems requirements and typically have a stronger systems development background than business analysts.

What are Project Data models?

more detailed view of data, matching data structure in database or data warehouse; allows you to find multiple attributes on a customer; it is more specific for the project team to design the database

What are the most common types of Relationships?

one-to-many (1:M) or many-to-many (M:N)

Users

provide assessments of their information needs and monitor that the developed system meets their needs.

Increased application development productivity

refers to the reduced cost and time for developing new business applications.

Logical Schema

representation of data for a type of data management technology

Because all the data is shared in a central database (in DBMS's), there is no longer the need for...

separate systems and programs to maintain their own copy of the data which reduces duplication

Enforcement of standards

single-point authority and responsibility for establishing and enforcing data standards. These standards include naming conventions, data quality standards, and uniform procedures for accessing, updating, and protecting data.

New, specialized personnel as a risk of the database approach

the cost of hiring new personel to use the databases may more than offset the increases in producitivity

A project begins with _____________, executed during ______________, and ends with ________________ (the SDLC steps)

the first steps of the Project Initiation and Planning phase; analysis, design and implementation; the last steps of the Implementation phase

What are relational databases?

the form of most current DBMS's; they represent data as a collection of tables in which all data relationships are represented by primary/foreign keys

Because applications are often developed independently in file processing systems, unplanned duplicate data files are ___________________________.

the rule rather than the exception.

Conversion costs as a risk of the database approach

very high cost to move from a legacy system to a database system and this can be prohibitive for some companies looking to make the switch

Business analysts

work with both management and users to analyze the business situation and develop detailed system and program specifications for projects.