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Data Management . MIS 503 Management Information Systems MBA Program. Definitions. Database: A DB is an organized collection of logically related data Data: stored representations of meaningful objects and events Structured: numbers, text, dates Unstructured: images, video, documents

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data management

Data Management

MIS 503Management Information Systems

MBA Program

definitions
Definitions
  • Database: A DB is an organized collection of logically related data
  • Data: stored representations of meaningful objects and events
    • Structured: numbers, text, dates
    • Unstructured: images, video, documents
  • Information: data processed to increase knowledge in the person using the data
  • Metadata: data that describes the properties and context of user data
data entities attributes and keys
Data Entities, Attributes, and Keys
  • An entity is a generalized class of people, places, or things for which data is collected, stored, and maintained.
  • A attribute is a characteristic of an entity.
  • Data item - a value of an attribute can be found in the fields of the record describing an entity.
slide4

Key Fields

  • Keys are special fields that serve two main purposes:
    • Primary keys are unique identifiers of the relation in question. Examples include employee numbers, social security numbers, etc. This is how we can guarantee that all rows are unique
    • Foreign keys are identifiers that enable a dependent relation (on the many side of a relationship) to refer to its parent relation (on the one side of the relationship)
    • A secondary key is a field in a record that does not uniquely identify the record but which is used to look up fields (e.g., Last Name) in, for example, and index
    • Candidate Key – an attribute that could be a key…satisfies the requirements for being a key
  • Keys can be simple (a single field) or composite (more than one field)
data model
Data Model
  • A data model is a diagram of entities and their relationships.
  • Data modeling involves understanding a specific business problem and analyzing the data and information needed to deliver a solution.
  • The data model will be optimized to balance storage efficiency and query efficiency
e r diagrams
E-R Diagrams
  • Entity-relationship (ER) diagrams use graphical diagrams to demonstrate the organization of and relationships between entities.
  • Relationships include:
    • one-to-many (1:N)
    • one-to-one (1:1)
    • many-to-many (N:M)
relational database model
Relational Database Model
  • Relational Model - the relational model describes data using a standard tabular format
    • All data elements are placed in two-dimensional tables, called relations
    • A relation contains rows (tuples, records) and columns (attributes, fields) with each intersecting cell containing an item of data
      • Each attribute has a domain, which is the structure or constraints on the type of data an attribute can hold
data management issues
Data Management Issues
  • Data redundancy – Un-needed duplication of data
  • Data integrity – Can we rely on the data?
    • Is it accurate?
    • Is it secure?
  • Program-data dependence - programs and data that are developed and organized so that the data is linked to the application program and the data is incompatible with other programs or data management tools
the database approach to data management
The Database Approach to Data Management
  • The database approach
    • Central repository of shared data
    • Data is managed by a controlling agent
    • Stored in a standardized, convenient form

To implement a database one must have a Database Management System (DBMS)

database management systems dbms
Database Management Systems (DBMS)

A database management system is a group of programs used as an interface between a database and application programs or a database and the user.

DBMSs are classified by the type of database model they support.

Modern information systems are usually built on data housed in one or more DBMS

slide13

TECHNICAL ASPECTS OF MANAGING THE DATA RESOURCE

Tools for Managing Data

  • A DBMS helps manage data by providing seven functions:
    • Data storage, retrieval, update
    • Backup
    • Recovery
    • Integrity control
    • Security control
    • Concurrency control
    • Transaction control

Page 139

advantages of dbmss
Advantages of DBMSs
  • Reduced data redundancy.
  • Improved data integrity.
  • Faster program development.
  • Easier modification and updating.
  • Data and program independence.
  • Standardization of data access.
  • A framework for program development.
  • Better overall protection of the data.
  • Shared data and information resources.
data normalization
Data Normalization
  • A common problem with data organization is that data are often not well organized
    • Anomalies are problems and irregularities in data.
    • Data anomalies often result in giving users incorrect information, causing them to be misinformed about actual business conditions.
  • If data are not well organized, the table may need to be normalized…
slide16

Well-Structured Relations

  • A relation that contains minimal data redundancy and allows users to insert, delete, and update rows without causing data inconsistencies
  • Goal is to avoid anomalies
    • Insertion Anomaly – adding new rows forces user to create duplicate data
    • Deletion Anomaly – deleting rows may cause a loss of data that would be needed for other future rows
    • Modification Anomaly – changing data in a row forces changes to other rows because of duplication

General rule of thumb: a table should not pertain to more than one entity type

an example of normalization
An Example of Normalization
  • Click here to view a step-by-step example of normalization
slide19

TECHNICAL ASPECTS OF MANAGING THE DATA RESOURCE

Database Architecture

Database –

shared collection of logically related data, organized to meet needs of an organization

Database Architecture –

way in which the data are structured and stored in the database

Page 137

database schemas
Database Schemas
  • Schema - a general description of the entire database that shows all of the record types and their relationships.
    • A user view (external schema) is the portion of the database a user can access.
    • The conceptual view is the logical design of the database (how should the database be organized regardless of physical constraints)
    • The internal view (physical view) is the physical storage structure for the database
  • A subschema shows only some of the records and their relationships in the database.
slide23
SQL
  • Structured Query Language - a query language is a specialized type of data manipulation language.
  • Query languages make retrieving information and manipulating a database easy and fast.
  • SQL - structured query language.
slide24

Structured Query Language (SQL)

  • Basic structure of a SQL expression
    • The select clause lists the attributes desired in answer to a query
    • The from clause is a list of relations or tables that the query language processor should consult in filling the request
    • The where clause describes the attributes desired in the answer
distributed databases
Distributed Databases
  • Distributed Processing - involves placing processing units at different locations and typing them together with data communications equipment and systems.
    • A distributed database is a database in which the actual data may be spread across several small databases connected via telecommunication devices.
storage area networks san
Storage Area Networks (SAN)
  • High-speed, special purpose network or subnet that interconnects different kinds of storage devices with associated data servers to benefit a larger network of users.
  • Part of an overall network for computing resources.
  • Usually physically located near larger computing resources such as a mainframe or server.
network attached storage nas
Network-Attached Storage (NAS)
  • Hard disk storage with its own network address rather than being attached to a server or workstation.
  • Includes:
    • Multi-disk Redundant Arrays of Integrated Disks (RAID) systems
    • Software to configure and map file locations
    • Designed to handle a variety of network protocols
slide29

The Data Warehouse

  • Businesses collect a tremendous amount of transactions data from routine operations
  • These data can be analyzed to understand the business better
    • Requires multidimensional analysis called Online Analytical Processing (OLAP)
    • Helps create a learning organization that is better able to understand its markets, customers and itself
slide30

Definition

  • Data Warehouse:
    • A subject-oriented, integrated, time-variant, non-updatable collection of data used in support of management decision-making processes
    • Subject-oriented: e.g. customers, patients, students, products
    • Integrated: Consistent naming conventions, formats, encoding structures; from multiple data sources
    • Time-variant: Can study trends and changes
    • Nonupdatable: Read-only, periodically refreshed
  • Data Mart:
    • A data warehouse that is limited in scope
slide31

Components of a star schema

Fact tables contain factual or quantitative data

Dimension tables are denormalized to maximize performance

1:N relationship between dimension tables and fact tables

Dimension tables contain descriptions about the subjects of the business

data mining
Data Mining
  • Discovers interesting structure in large amounts of data
  • This structure consists of
    • Patterns
    • Statistical or predictive models of the data
    • Relationships between the data
  • Applied extensively to customer data
    • Allows firms to determine for instance which products sell together
slide35

Object-Oriented Databases

  • Traditionally relational databases supported a limited number of data types
    • Alphabet, numeric, dates, and time
  • Modern organizations use a variety of data
    • Graphics objects, audio clips, videos, subscripted arrays, and complex data for data mining
  • RDBMS vendors have extended their packages to handle such data objects
slide36

Threats to Data Security

  • Accidental losses attributable to:
    • Human error
    • Software failure
    • Hardware failure
  • Theft and fraud.
  • Improper data access:
    • Loss of privacy (personal data)
    • Loss of confidentiality (corporate data)
  • Loss of data integrity
  • Loss of availability (through, e.g. sabotage)
slide37

Data Management Security Techniques/Procedures

  • Views or subschemas
  • Integrity controls
  • Authorization rules
  • User-defined procedures
  • Encryption
  • Authentication schemes
  • Backup, journalizing, and checkpointing
m anagerial i ssues in m anaging d ata
MANAGERIAL ISSUES IN MANAGING DATA

Principles in Managing Data

  • The need to manage data is permanent
  • Data can exist at several levels
  • Application software should be separate from the database
  • Application software can be classified by how they treat data
    • Data capture
    • Data transfer
    • Data analysis and presentation

Page 140

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MANAGERIAL ISSUES IN MANAGING DATA

Principles in Managing Data

  • Application software should be considered disposable
  • Data should be captured once
  • There should be strict data standards

Page 143

m anagerial i ssues in m anaging d ata2
MANAGERIAL ISSUES IN MANAGING DATA

The Data Management Process

Page 144

Figure 5.6 Asset Management Functions

m anagerial i ssues in m anaging d ata3
MANAGERIAL ISSUES IN MANAGING DATA

Data Management Policies

  • Organizations should have policies regarding:
    • Data ownership
    • Data administration

Page 148

m anagerial i ssues in m anaging d ata4
MANAGERIAL ISSUES IN MANAGING DATA

Data Ownership

Corporate information policy–

foundation for managing the ownership of data

Page 148

slide43

Page 149

Figure 5.8 Example Data Access Policy

m anagerial i ssues in m anaging d ata5
MANAGERIAL ISSUES IN MANAGING DATA

Data Administration

Key functions of the data administration group:

  • Promote and control data sharing
  • Analyze the impact of changes to application systems when data definitions change
  • Maintain the data dictionary
  • Reduce redundant data and processing
  • Reduce system maintenance costs and improve system development productivity
  • Improve quality and security of data
  • Insure data integrity

Page 150

m anagerial i ssues in m anaging d ata6
MANAGERIAL ISSUES IN MANAGING DATA

Data Administration

Key functions of the database administrator (DBA):

  • Tuning database management systems.
  • Selection and evaluation of and training on database technology.
  • Physical database design.
  • Design of methods to recover from damage to databases.
  • Physical placement of databases on specific computers and storage devices.
  • The interface of databases with telecommunications and other technologies.

Page 150-151

slide46

7 Habits of Highly Effective Data Modelers*

  • Immerse
    • Immerse yourself in the task environment to find out what the client wants
  • Challenge
    • Challenge existing assumptions; dig out the exceptions and test the boundaries of the model
  • Generalize
    • Reduce the number of entities whenever possible; simpler is easier to understand
  • Test
    • Read it to yourself and to others to see if it makes sense and is relevant to the problem *adapted from R. Watson (1999)
slide47

7 Habits of Highly Effective Data Modelers

  • Limit
    • Set reasonable limits to the time and scope of the data modeling activities. Identify the core entities and attributes that will solve the problem and stick to those
  • Integrate
    • Identify how your project’s model fits with the organization’s information architecture. Can it be integrated with the corporate data model? Look at the big picture.
  • Complete
    • Don’t leave the data model ill-defined. Define entities, attributes, and relationships carefully.
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