2. The Hierarchy of Data
Bit (a binary digit): a circuit that is either on or off
Byte: 8 bits
Character: each byte represents a character; the basic building block of information
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
Hierarchy of data
Bits, characters, fields, records, files, and databases

3. Data Entities, Attributes, and Keys
Entity: a generalized class of people, places, or things (objects) for which data is collected, stored, and maintained
Attribute: a characteristic of an entity
Data item: a value of an attribute
Key: field(s) that identify a record
Primary key: field(s) that uniquely identify a record
Figure 3.2: Keys and Attributes

4. The Traditional Approach
Traditional approach: separate data files are created for each application
Results in data redundancy (duplication)
Data redundancy conflicts with data integrity
Database approach: pool of related data is shared by multiple applications
Significant advantages over traditional approach
The database approach to data management provides significant advantages over the traditional file-based approach.
Define general data management concepts and terms, highlighting the advantages of the database approach to data management.
Describe the relational database model and outline its basic features.
Figure 3.3: The Traditional Approach to Data Management

5. The Database Approach
Figure 3.4: The Database Approach to Data Management

6. Advantages of the Database Approach

7. Disadvantages of the Database Approach

8. 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?

9. 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 organization’s information needs
Physical design
Fine-tunes the logical database design for performance and cost considerations

10. Data Modeling (continued)
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
Figure 3.5: An Entity-Relationship (ER) Diagram for a Customer Order Database

11. The Relational Database Model
Relational model: all data elements are placed in two-dimensional tables (relations), which are the logical equivalent of files
Relational model: all data elements are placed in two-dimensional tables (relations), which are the logical equivalent of files
In the relational model:
Each row of a table represents a data entity
Columns of the table represent attributes
Domain: the allowable values for data attributes
Figure 3.6: A Relational Database Model

12. Manipulating Data Figure 3.8: Linking Data Tables to Answer an Inquiry
Linking: relates or links two or more tables using common data attributes very useful when info is needed from multiple tables
Figure 3.8: Linking Data Tables to Answer an Inquiry

13. Database Management Systems (DBMS)
Interface between
Database and application programs
Database and the user

14. Basic DBMS Functions: Providing user views
Creating and modifying databases
Storing and retrieving data
Manipulating data
Generating reports

15. 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

16. Providing a User View (continued)
One of the first steps in installing and using a database involves telling the DBMS the logical and physical structure of the data and the relationships among the data in the database. This description is called a schema. If there is a need to create different user views, or portions of the database that particular users can access, subschemas will need to be developed. A subschema is a file that contains a description of a subset of the database and identifies which users can view and modify the data items in that subset.
Figure 3.10: The Use of Schemas and Subschemas

17. 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
Creating and Modifying the Database
Schemas and subschemas are entered into the DBMS via a data definition language. A data definition language (DDL) is a collection of instructions and commands used to define and describe data and data relationships in a specific database.

18. Creating and Modifying the Database (continued)
Schemas and subschemas are entered into the DBMS via a data definition language. A data definition language (DDL) is a collection of instructions and commands used to define and describe data and data relationships in a specific database.
Figure 3.12: A Typical Data Dictionary Entry

19. Storing and Retrieving Data
When an application requests data from the DBMS, the application follows a logical access path
When the DBMS goes to a storage device to retrieve the requested data, it follows a path to the physical location (physical access path) where the data is stored
Storing and Retrieving Data
A DBMS functions as an interface between an application program and the database. When an application program needs data, it requests that data through the DBMS. When an application program requests data from the DBMS, the application program follows a logical access path. Next, the DBMS, working in conjunction with various system software programs, accesses a storage device, such as disk or tape, where the data is stored. When the DBMS goes to this storage device to retrieve the data, it follows a path to the physical location (physical access path, or PAP) where the data is stored.

20. Storing and Retrieving Data (continued)
Figure 3.13: Logical and Physical Access Paths

21. Manipulating Data and Generating Reports
Query-By-Example (QBE): a visual approach to developing database queries or requests
Data manipulation language (DML): commands that manipulate the data in a database
Structured Query Language (SQL): ANSI standard query language for relational databases
Database programs can produce reports, documents, and other outputs
Manipulating Data and Generating Reports
Query-By-Example (QBE) is a visual approach to developing database queries or requests. Another approach is the use of a programming language. The commands that are used to manipulate a database are part of the data manipulation language (DML). Structured Query Language (SQL) is a data manipulation language that has been adopted by the American National Standards Institute (ANSI) as the standard query language for relational databases.

22. Manipulating Data and Generating Reports (continued)
Figure 3.16: Database Output

23. 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
Database Administration
A database administrator (DBA) is a highly skilled systems professional who directs or performs all activities to maintain a successful database environment. The DBA’s responsibilities include designing, implementing, and maintaining the database system and the DBMS; establishing policies and procedures pertaining to the management, security, maintenance, and use of the database management system; and training employees in database management and use.

24. Popular Database Management Systems
Popular DBMSs for end users: Microsoft Access and Corel Paradox
The complete database management software market includes databases by IBM, Oracle, and Microsoft
Examples of open-source database systems: PostgreSQL and MySQL
Many traditional database programs are now available on open-source operating systems
Popular Database Management Systems
The latest generation of database management systems makes it possible for end users to build their own database applications. End users are using these tools to address everyday problems, such as how to manage a mounting pile of information on employees, customers, inventory, or sales. These database management systems are an important personal productivity tool along with word processing, spreadsheet, and graphics software.
A key to making DBMSs more usable for some databases is the incorporation of “wizards,” which walk you through how to build customized databases, modify ready-to-run applications, use existing record templates, and quickly locate the data you want. These applications also include powerful new features, such as help systems and Web-publishing capabilities. For example, users can create a complete inventory system and then instantly post it to the Web, where it does double duty as an electronic catalog.
Some of the more popular DBMSs for end users include Microsoft’s Access and Corel’s Paradox. Popular options among the DBMSs used by professional programmers include products from IBM, Oracle, and Microsoft. A number of open-source database systems are also available, including PostgreSQL and MySQL.

25. Special-Purpose Database Systems
Summation and Concordance (law firms)
CaseMap (law firms)
LiveNote (display and analyze transcript)
Scottish Intelligence Database (SID)
GlobalSpec ( engineer )
Special-Purpose Database Systems
A number of specialized database packages are used for specific purposes or in specific industries. Examples of such systems include Summation and Concordance, used in law firms; the Scottish Intelligence Database (SID), used by the Scottish Drug Enforcement Agency; and GlobalSpec, used by engineers and product designers.

26. 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

27. Using Databases with Other Software
Database management systems are often used with other software packages or the Internet
A database management system can act as a front-end application or a back-end application
Front-end application: interacts with users
Back-end application: interacts with applications
The number and types of database applications will continue to evolve and yield real business benefits.
Identify and briefly discuss current database applications.
Using Databases with Other Software
Database management systems are often used in conjunction with other software packages or the Internet. A database management system can act as a front-end application or a back-end application. A front-end application is one that directly interacts with people or users. A back-end application interacts with other programs or applications; it only indirectly interacts with people or users.

28. Database Applications: Linking the Company Database to the Internet
Corporate databases can be accessed by customers, suppliers, and employees through:
The Internet
Intranets
Extranets
Semantic Web: Developing a seamless integration of traditional databases with the Internet

29. Data Warehouses, Data Marts, and Data Mining
Data warehouse: collects business information from many sources in the enterprise
Data mart: a subset of a data warehouse
Data mining: an information-analysis tool for discovering patterns and relationships in a data warehouse or a data mart

30. Data Warehouses, Data Marts, and Data Mining (continued)
Figure 3.17: Elements of a Data Warehouse

31. Data Warehouses, Data Marts, and Data Mining (continued)
Table 3.3: Common Data-Mining Applications

32. Business Intelligence
Business intelligence (BI): gathering the right information in a timely manner and usable form and analyzing it to have a positive impact on business
Knowledge management: capturing a company’s collective expertise and distributing it wherever it can help produce the biggest payoff

33. Distributed Databases
Data may be spread across several smaller databases connected via telecommunications devices
Corporations get more flexibility in how databases are organized and used
Replicated database
Holds a duplicate set of frequently used data

34. Online Analytical Processing (OLAP)
Software that allows users to explore data from a number of different perspectives
Table 3.4: Comparison of OLAP and Data Mining

35. Object-Oriented and Object-Relational Database Management Systems
Object-oriented database
Stores both data and its processing instructions
Method: a procedure or action
Message: a request to execute or run a method

36. Object-Oriented and Object-Relational Database Management Systems (continued)
Object-oriented database management system (OODBMS)
Programs that manipulate an object-oriented database and provide a user interface and connections to other application programs
Object-relational database management system (ORDBMS)
A DBMS capable of manipulating audio, video, and graphical data

37. Visual, Audio, and Other Database Systems
Visual database systems
Audio database systems
Virtual database systems
Spatial data technology