Mgt 20600: IT Management

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Mgt 20600 IT Management ApplicationsDatabase
s

• Tuesday
• April 4, 2006

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Reminders

• Reading
• For today
• Fundamentals text, Chapter Three, Organizing Data
  and Information
• For next class on April 11th
• Fundamentals text, Chapter Six, Information and
  Decision Support Systems
• Homework
• Homework Four
• Databases
• Due Thursday, April 14th
• Next week Decision Support Systems

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Databases

• A well-designed and well-managed database is an
  extremely valuable tool in supporting decision
  making
• Databases are key corporate assets
• Databases are the foundation for sophisticated
  analyses that provide business intelligence
• What new products to design
• How to market to particular customer groups
• Which customer groups are the most profitable

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Traditional Approach to Data Management
Traditional approach separate data files are
created for each application Results in data
redundancy (duplication) Data redundancy
conflicts with data integrity
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Database Approach to Data Management
Database approach pool of related data is shared
by multiple applications Significant advantages
over traditional approach
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Advantages of Database Approach

• Improved strategic use of data
• Reduced data redundancy
• Improved data integrity
• Easier modification and updating
• Data and program independence
• Better access to data and information
• Standardization of data access
• A framework for program development
• Better overall protection of the data
• Shared data and information resources

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Disadvantages of the Database Approach

• More complexity
• More difficult to recover from a failure
• More expensive

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Databases

• Databases must contain
• Accurate information
• Right kinds of information
• Current information
• Information from all organizational functions

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Database Data

• Data regarding
• Important entities
• Customers
• Suppliers
• Transactions
• Each entity will have a number of attributes
  about which you want to collect and store
  information
• Customer address
• Customer phone number
• Customer account number

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Entities, Attributes, Keys
Entity a generalized class of people, places, or
things (objects) for which data is collected,
stored, and maintained (Table and
records) Attribute a characteristic of an entity
(fields) Data item a value of an attribute
(fields) Key field(s) that identify a
record Primary key field(s) that uniquely
identify a record
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Hierarchy of Data
Field name, number, or characters that describe
an aspect of a business object or activity
Record a collection of related data fields File
a collection of related records Database a
collection of integrated and related files
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Data Modeling and the Relational Database Model

• When building a database, consider
• Content What data should be collected, at what
  cost?
• Access What data should be provided to which
  users, and when?
• Logical structure How should data be arranged to
  make sense to a given user?
• Physical organization Where should data be
  physically located?

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Data Modeling

• Building a database requires two types of design
• Logical design
• Shows an abstract model of how data should be
  structured and arranged to meet an organizations
  information needs
• Physical design
• Fine-tunes the logical database design for
  performance and cost considerations

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Data Modeling

• Data model a diagram of data entities and their
  relationships
• Entity-relationship (ER) diagrams data models
  that use basic graphical symbols to show the
  organization of and relationships between data

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Data Modeling
An Entity-Relationship (ER) Diagram for a
Customer Order Database
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The Relational Database Model

• Relational model all data elements are placed in
  two-dimensional tables (relations), which are the
  logical equivalent of files
• In the relational model
• Each table represents a data entity
• Each row of a table represents a specific
  instance of a data entity
• Columns of the table represent attributes

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The Relational Database Model
A Relational Database Model
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Creating and Modifying the Database

• Data definition language (DDL)
• Collection of instructions/commands that define
  and describe data and data relationships in a
  database
• Allows database creator to describe the data and
  the data relationships that are to be contained
  in the schema and the subschemas
• Data dictionary a detailed description of all
  the data used in the database

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Storing and Retrieving Data
Logical and Physical Access Paths
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Providing a User View

• Schema description of the entire database
• User view user-accessible portion of the
  database
• Subschema
• Contains a description of a subset of the
  database
• Identifies which users can view and modify the
  data items in the subset
• Is used to create different user views

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Providing a User View
The Use of Schemas and Subschemas
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Creating and Modifying the Database
A Typical Data Dictionary Entry
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Manipulating Data and Generating Reports

• Data manipulation language (DML) commands that
  manipulate the data in a database
• Query-By-Example (QBE) a visual approach to
  developing database queries or requests
• Structured Query Language (SQL) ANSI standard
  query language for relational databases
• Database programs can produce reports, documents,
  and other outputs

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Manipulating Data

• Selecting eliminates rows according to criteria
• Projecting eliminates columns in a table
• Joining combines two or more tables
• Linking relates or links two or more tables
  using common data attributes

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Manipulating Data
Linking Data Tables to Answer an Inquiry
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Database Administration

• Database administrator (DBA) directs or performs
  all activities to maintain a database environment
• Designing, implementing, and maintaining the
  database system and the DBMS
• Establishing policies and procedures
• Training employees

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Selecting a Database Management System

• Important characteristics of databases to
  consider
• Size of the database
• Number of concurrent users
• Performance
• Ability to be integrated with other systems
• Features of the DBMS
• Vendor considerations
• Cost of the system