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LEARNING OBJECTIVES• The importance of high-quality information and issues involved in managing business data.
• Advantages of the Database approach.• Data Modeling and Database Design with Entity Relationship Diagram (ERD)
• How organizations can maximize their strategic potential with databases : Data Warehouse, Data Marts, Data Mining, Business Intelligence
Information Quality• Business decisions are only as good as the quality of the information used to make the decisions
• Characteristics of High-quality Information• Accurate• Complete• Consistent• Unique• Timely
The Costs Of Using Low-quality Information• The four primary sources of low quality
information include
1. Customers intentionally enter inaccurate information to protect their privacy
2. Different entry standards and formats
3. Operators enter abbreviated or erroneous information by accident or to save time
4. Third party and external information contains inconsistencies, inaccuracies, and errors
The Costs Of Using Low-quality Information . . .• Potential business effects resulting from low quality information include• Inability to accurately track customers• Difficulty identifying valuable customers• Inability to identify selling opportunities• Marketing to nonexistent customers• Difficulty tracking revenue• Inability to build strong customer relationships
The Benefits Of Good Information • High quality information can significantly improve the chances of making a good decision
• Good decisions can directly impact an organization's bottom line
Information Timeliness
• Real-time information – Immediate, up-to-date information
• Real-time system – Provides real-time information in response to requests
Difficulties in Managing Business Data
• Amount of data increases exponentially.• Data are scattered and collected by many individuals using various methods and devices.
• Data come from many sources.• Data security, quality and integrity are critical.• An ever-increasing amount of data needs to be considered in making organizational decisions.
Data Management• File Processing Systems
• Stand-alone applications with their own data files.• Data are NOT shared across applications• Redundancy , Inaccurate
• DBMS – Database Management Systems• Use a DBMS software to create, store, organize, and
retrieve data from a single database or several databases
• Examples: Microsoft Access, SQL Server, Oracle
Conventional Files vs. the DatabaseFile – a collection of similar records.
• Files are unrelated to each other except in the code of an application program.
• Data storage is built around the applications that use the files.
Database – a collection of interrelated files• Records in one file (or table) are physically related to
records in another file (or table).• Applications are built around the integrated database
Difficulties of Non-Relational Data Files
• Update Anomaly: not changing all occurrence of a data item (in many places)
• Insert Anomaly: add an invalid (null record) to the database
• Delete Anomaly: not remove all info (in many places) about a deleted record
Database Management System (DBMS)
Database
Record
File
Field Individual characteristics/attributes about an ENTITY. (Also called columns)
A group of fields or attributes to describe a single instance/member of an ENTITY. (Also called rows)
A collection of records or instances for a given ENTITY. (Also called tables)
A collection of files or entities containing information to support a given system or a particular topic area
Main Database Activities/Functions• Recording Data (Input)
• Entry Form• Processing Data (Query)
• Structured Query Language (SQL)• Query by example (QBE)
• Reporting Data (Output)• Report – a compilation of data that is organized and
produced in printed format• Report Generators
The Database Approach• DBMS provides all users with access to all the data.
• DBMS minimize the following problems:• Data redundancy• Data isolation• Data inconsistency
• DBMS maximizes the following issues:• Data security• Data integrity• Data independence
Using A Relational Database For Business Advantages• Database advantages from a business perspective include• Increased flexibility• Increased scalability and performance• Reduced information redundancy• Increased information integrity (quality)• Increased information security
Increased Flexibility• A well-designed database should
• Handle changes quickly and easily• Provide users with different views• Have only one physical view
• Physical view – Deals with the physical storage of information on a storage device
• Have multiple logical views• Logical view – Focuses on how individual users logically access
information to meet their own particular business needs
Increased Scalability & Performance• A database must scale to meet increased demand, while maintaining acceptable performance levels• Scalability – Refers to how well a system can
adapt to increased demands• Performance – Measures how quickly a system
performs a certain process or transaction
Database Approach• Advantages of the Database Approach
• Program-data independence• Minimal data redundancy• Improved data consistency• Improved data sharing• Increased productivity of application development• Enforcement of standards• Improved data quality• Improved data accessibility• Reduced program maintenance
Database Approach . . .• Costs/Risks of the Database Approach
• New, specialized personnel• Installation/management cost and complexity• Conversion cost: what to do with legacy systems
(old data)• Need for explicit backup and recovery• Data ownership: organizational conflict
Student ID
Last Name
First Name
2144 Arnold Betty
3122 Taylor John
3843 Simmons Lisa
9844 Macy Bill
2837 Leath Heather
2293 Wrench Tim
Record / Row
Field / ColumnData Hierarchy
File / Table
Database
Database Components
Database Engine
Database
Form Builder
ReportWriter
Interactive Query Tool
ApplicationProgram
DatabaseFront-end
DatabaseGatewayTo other
computer systems To other DBMS brands
Data Modeling• ERD (Entity Relationship Diagram)
Blue print of Relational Database• Entity (object / info of interest)• Attributes (characteristics / fields)• Relationship (business rules)
Entities• Entity is a group of attributes corresponding to the same conceptual thing about which we need to capture and store data (in a file/table)
• Entity is a set of instances / members of the object that it represents (records)
• Entity must have a unique name, unique identifier, and at least one attribute (the identifier itself is sufficient)
• Persons: agency, contractor, customer, department, division, employee, instructor, student, supplier.
• Places: sales region, building, room, branch office, campus.
• Objects: book, machine, part, product, raw material, software license, software package, tool, vehicle model, vehicle.
• Events: application, award, cancellation, class, flight, invoice, order, registration, renewal, requisition, reservation, sale, trip.
• Concepts: account, block of time, bond, course, fund, qualification, stock.
Entities: Examples
Entity Instance: ExampleEntity instance – a single member of an entity.
Student ID Last Name First Name
2144 Arnold Betty
3122 Taylor John
3843 Simmons Lisa
9844 Macy Bill
2837 Lea Heather
2293 Wrench Tim
Entity
Instances
Attributes
Attributes• An attribute is a descriptive property or characteristic of interest of an entity. Also called field.
• The data type for an attribute defines what type of data can be stored in that attribute.
• The domain of an attribute defines what values an attribute can legitimately take on.
• The default value for an attribute is the value that will be recorded if not specified by the user.
Entities & Attributes . . .
ENTITY NAME
- entity id - attribute 1 - attribute 2 - …………..
- attribute n
CUSTOMER
- Customer_ID- Cust_Name - Cust_Address
- Cust_Phone
Attributes• Simple vs. composite
• Single-valued vs. multi-valued
• Stored vs. derived
• Null-valued
Simple Vs. Composite• Composite attributes can be divided into smaller subparts, which represent more basic attributes that have their own meanings
• Address can be broken down into a number of subparts, such as Street, City, State, Zip Code
• Street may be further broken down by Number, Street Name, and Apartment/Unit Number
• Attributes that are not divisible into subparts are called simple attributes
Single-valued Vs. Multi-valued• Single-valued attribute means having only a single value of each attribute of an entity at any given time• A CUSTOMER entity allows only one Telephone Number for
each CUSTOMER• If a CUSTOMER has more than one Phone Number and wants
them all included in the database, then CUSTOMER entity cannot handle them
Multi-valued• Multi-valued attribute means having the potential to
contain more than one value for an attribute at any given time
• An entity in a relational database cannot have multi-valued attributes, must create another entity to hold them
• Relational databases do not allow multi-valued attributes because they can cause problems: • Confuses the meaning of data in the database• Significantly slow down searching• Place unnecessary restrictions on the amount of
data that can be stored
Stored Vs. Derived• If an attribute can be calculated using the value of
another attribute, it is called a derived attribute
• The attribute that is used to derive the attribute is called a stored attribute
• Derived attributes are not stored in the file, but can be derived when needed from the stored attributes
Null-valued• Null-valued attribute – Assigned to an attribute when no other value applies or when a value is unknown