1. Organizing Data & Information
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Organizing Data & Information

2. Data & Databases
Data consists of raw facts that when organized may be transformed into information
A Database is a collection of data organized to meet users’ needs
A Database Management System (DBMS) is
a group of programs that manipulate the database & provide an interface between the database & the user of the database or other application programs
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3. The Hierarchy of Data (Figure 5.1)
Database Management System
Database
File (table)
Record (entity, row)
Field (characteristic, column)
Byte (character)
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4. Data Entities, Attributes, & Keys
Entity: A generalized class of people, places, or things for which data is collected, stored, & maintained
Examples: customers, employees
Attribute: A characteristic of an entity; something the entity is identified by
Examples: customer name, employee name
Key: A field or set of fields in a record that is a unique identifier of a record
Examples: social insurance number, customer number
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5. Keys & Attributes (Figure 5.2)
Employee
Number
Last Name
First Name
Hire Date
Department
Johns
Francine
257
Buckley
Bill
650
Fiske
Steven
1-5-85
598
< Entities >
(records)
Key Field
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6. The Traditional Approach (Figure 5.3)
Separate files are created & stored for each application program
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7. Drawbacks to the Traditional Approach
Data redundancy
Duplication of data in separate files
Lack of data integrity
The degree to which the data in any one file is accurate
Program-data dependence
A situation in which programs & data organized for one application are incompatible with programs & data organized differently for another application
Inability to Link Data
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8. The Database Approach (Figure 5.4)
A pool of related data is shared by multiple applications. Rather than having separate data files, each application uses a collection of data that is either joined or related in the database.
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9. Advantages to the Database Approach
Improved strategic use of corporate data
Reduced data redundancy
Improved data integrity
Easier modification & updating
Data & program independence
Better access to data & information
Standardization of data access
A framework for program development
Better overall protection of the data
Shared data & information resources
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10. Disadvantages to the Database Approach
Relatively high cost of purchasing & operating a DBMS in a mainframe operating environment
Increased cost of specialized staff
Increased vulnerability
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11. Database Design Logical design precedes physical design
Abstract model of how data should be structured & arranged
Users should assist in creating logical design
Physical design starts with the logical design
What specific hardware/software will be used
Fine-tuning of logical design for performance/cost considerations
Planned Data Redundancy
A way of organizing data in which the logical database design is altered so that certain data entities are combined
Summary totals are carried in the data records rather than calculated from elemental data
Some data attributes are repeated in more than one data entity to improve database performance
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12. Data Modeling Data Model Enterprise data modeling
A map or diagram of entities & their relationships
Enterprise data modeling
Data modeling done at the level of the entire organization
Entity-Relationship (ER) diagrams
A data model that uses basic graphical symbols to show the organization of & relationships between data (Figure 5.5)
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13. Database Models
Hierarchical (Figure 5.6): A data model in which the data is organized in a top-down or inverted tree structure
Network (Figure 5.7): An expansion of the hierarchical database model with an owner-member relationship in which a member may have many owners
Relational (Figure 5.8): All data elements are placed in two-dimensional tables, called relations, that are the logical equivalent of files
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14. A Relational Database (3 tables)
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15. Relational Database Terminology
Domain: Allowable values for attributes
Selecting: Data manipulation that eliminates rows (records) according to user-defined criteria
Projecting: Data manipulation that eliminates columns (attributes) in a table
Joining: Data manipulation that combines two or more tables
Linking: Relating tables in a relational database together by a common attribute(s)
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16. Schemas & Subschemas Schema Subschema View of the entire database
Includes logical & physical structure & relationships among all data
Subschema
User view of a portion of the database
Can have many subschemas for one database
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17. Data Definition Language & Dictionary
Data Definition Language (DDL)
A collection of instructions & commands used to define & describe data & data relationships in a database
Data Dictionary
A detailed description of all data used in the database
Provides a standard definition of terms & data elements
Assists programmers in designing & writing programs
Simplifies database modification
Reduces data redundancy
Increases data reliability
Faster program development
Easier modification of data & information
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18. Logical & Physical Access Paths (Figure 5.14)
Data on
Storage
Device
Physical Access Path
DBMS accesses a storage device to retrieve data
DBMS
Logical Access Path
Application requires information from the DBMS
Management
inquiries
Other
Software
Application
Programs
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19. Manipulating Data Concurrency Control Data Manipulation Language (DML)
A method of dealing with a situation in which two or more people need to access the same record in a database at the same time
Data Manipulation Language (DML)
The commands that are used to manipulate the data in a database
Structured Query Language (SQL)
A standardized data manipulation language for querying a database
Most modern databases are SQL compliant
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20. DBMS Selection Criteria
Database size
Number of concurrent users
Performance
Integration
Features
Vendor
Cost
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21. Database Developments (1)
Distributed Database
A database in which the actual data may be spread across several smaller databases connected via telecommunications devices
Transparent to user (user does not know where data is)
Replicated Database
Duplicate of original database (saves telecom time/$$)
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22. Database Developments (2)
Data Warehouse
A relational database management system designed specifically to support management decision making
Data Mart
A subset of a data warehouse for small & medium-size businesses or departments within larger companies
Data Mining
Automated discovery of patterns & relationships in a data warehouse
Built-in analysis tools
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23. Database Developments (3)
On-line Transaction Processing (OLTP)
TP happens at time of transaction
On-line Analytical Processing (OLAP)
Supports high speed analysis of data involving complex relationships
Multidimensional Databases
Data can include graphics, photographs, sound files, etc.
Open Database Connectivity (ODBC)
Software written in compliance with ODBC standards can be used with any ODBC-compliant database
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24. Object-Relational Database Management Systems
Can manipulate audio, video, & graphical data
Hypertext: Users can search & manipulate alphanumeric data in an unstructured way
Hypermedia: Users can search & manipulate multimedia forms of data
Spatial Data Technology: Use of an object-relational database to store & access data according to the location it describes & to permit spatial queries & analysis
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25. Case
US West
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