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Chapter 13 Databases and Information Management

Chapter 13 Databases and Information Management

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Chapter 13 Databases and Information Management

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  1. Chapter 13Databases and Information Management

  2. Chapter 13 Objectives Next Explain why data and information are important to an organization Explain how to use a query language Identify file maintenance techniques Understand how Web databases work Differentiate between the file processing and database approaches Discuss the responsibilities of the database analysts and administrators Discuss the advantages of using a database management system (DBMS) Identify the qualities of valuable information Describe characteristics of relational and object-oriented databases Describe the various types of information systems Understand the concept of a data warehouse p. 13.2

  3. What is data? A collection of raw unprocessed facts, figures, and symbols Data and Information Next p. 13.2 Fig. 13-1

  4. What is information? Data that is organized, meaningful, and useful Data and Information Next p. 13.2 Fig. 13-1

  5. How are data and information related? Computers process data into information Data and Information Next p. 13.2 Fig. 13-1

  6. What is a database? Includes a collection of data organized so you can access, retrieve, and use the data Database software allows you to Create a computerized database Add, change, and delete data Sort and retrieve data from the database Create forms and reports for the data in the database Database software also called a database management system (DBMS) Data and Information Next p. 13.2

  7. What is data integrity? The degree to which data is correct When a database contains errors, it loses integrity Very important because computers and people use information to make decisions and take actions Data and Information Garbage in, garbage out (GIGO) You cannot create correct information from data that is incorrect Next p. 13.3

  8. What is a field? A combination of one or more characters The smallest unit of data a user accesses A field name uniquely identifies each field The Hierarchy of Data Character A number (4), letter (R), punctuation mark (?), or other symbol (&) fields Next p. 13.4 Fig. 13-3

  9. What are characteristics of a field? Data type Specifies the kind of data a field can contain Specifies how the field is used Field size Defines the maximum number of characters a field can contain The Hierarchy of Data Text – letters, numbers, or special characters Numeric – numbers only Currency – dollar and cent amounts or numbers containing decimal values Date – month, day, year, and sometimes time information Memo – lengthy text entries Yes/No – only the values Yes or No Hyperlink – Web address that links to a document or a Web page Object – picture, audio, video, or a document created in other applications such as word processing or spreadsheet Next p. 13.5

  10. What is a record? A group of related fields The Hierarchy of Data field names maximum characters in Rating field records key fieldA field that uniquely identifies each record in a file Also called a primary key Next p. 13.5 Fig. 13-2

  11. What is a data file? Also called a file A collection of related records stored on a disk Each record in the file contains the same fields Each field contains different data The Hierarchy of Data fields Next records Sample Customer File p. 13.5 Fig. 13-3

  12. What is file maintenance? Also called data maintenance The procedures that keep data current Maintaining Data Adding records Changing records Deleting records Next p. 13.6

  13. How are records added? A clerk uses a Customer Maintenance program to add a new record The clerk enters the data for each field of the record The clerk takes a photograph with a digital camera and confirms the data is correct The clerk then adds the record to the database file Maintaining Data Next p. 13.6 Fig. 13-4

  14. How are records changed? The clerk starts the Customer Maintenance program The clerk displays the customer record on the screen The clerk makes the corrections The clerk verifies the data and then clicks the Save button to change the record in the Customer file Maintaining Data Records changed to correct inaccurate data or to update old data with new data Next p. 13.6 Fig. 13-5

  15. How is data deleted? The clerk starts the Customer Maintenance program The clerk displays the customer record on the screen The clerk confirms the correct customer record displays The clerk clicks the Delete Record button Maintaining Data A record can be flagged, or marked, so the program will not process it again Next p. 13.8 Fig. 13-6

  16. What is validation? The process of comparing data to a set of rules or values to find out if the data is correct A validity check analyzes entered data to help ensure that it is correct Validity checks are also called validation rules Maintaining Data Next Click to view Web Link then click Validity Checks p. 13.9 Fig. 13-7

  17. What are the types of validity checks? Maintaining Data Alphabetic check Ensures that you enter only alphabetic data into a field Numeric check Ensures that you enter only numeric data into a field Completeness check Verifies a required field contains data Consistency check Tests if the data in two or more associated fields is logical Range check Determines whether a number is within a specified range Check digit Confirms the accuracy of a primary key value Next p. 13.9

  18. What is an example of a completeness check? If you do not fill in a required field, an error message usually displays stating which required fields you left blank Maintaining Data Next p. 13.10 Fig. 13-8

  19. A number(s) or character(s) that is appended to or inserted into a primary key value Used to confirm the accuracy of a primary key value When the primary key is entered, the program applies the check digit formula to determine if the primary key is valid What is a check digit? Maintaining Data Initial primary key: 1367 Calculate total of digits: 1 + 3 + 6 + 7 = 17 Calculate total of digits again: 1 + 7 = 8 Check digit = 8 Resulting primary key: 13678 Next p. 13.10

  20. What is a file processing system? Each department or area within an organization has its own set of files Records in one file often do not relate to the records in any other file File Processing Versus Databases Next p. 13.11 Fig. 13-9

  21. What are the weaknesses of a file processing system? File Processing Versus Databases • data redundancy • The files often store the same fields in multiple files • Wastes resources such as storage space and people’s time • Requires a larger storage capacity • Compromises data integrity • isolated data • It is often difficult to access data stored in many files across several departments • Sharing data from multiple, separate files is often a complicated procedure Next p. 13.11

  22. What is the database approach? Many programs and users can share the data in the database Secures the data so only authorized users can access certain data items File Processing Versus Databases Back end The application that supports the front end Front end A program that typically has a more user-friendly interface than the DBMS Next p. 13.12 Fig. 13-10

  23. What are the strengths of the database approach? File Processing Versus Databases Reduced data redundancy Improved data integrity Shared data Reduced development time Easier reporting Next p. 13.13

  24. How do a database application and a file processing application differ in the way they might store data? File Processing Versus Databases File processing example Database example Next p. 13.13 Fig. 13-11

  25. What is a database management system (DBMS)? Software that allows you to create, access, and manage a database Available for many sizes and types of computers Database Management Systems Next Click to viewanimation Click to view Web Link then click Database Management Systems p. 13.14 Fig. 13-12

  26. What is a data dictionary? Also called a repository Contains data about each file in the database and each field within those files Sometimes called metadata because it contains data about data Database Management Systems Next Click to view Web Link then click Data Dictionary p. 13.15 Fig. 13-13

  27. What is a default value for a field? A value that the DBMS initially displays in a field Data dictionary allows you to specify a default value for a field Database Management Systems Next p. 13.15

  28. What is a query? A request for specific data from the database Four commonly used methods to access data Database Management Systems Query language Query by example Form Report generator Next Click to viewanimation p. 13.15

  29. What is a query language? Consists of simple, English-like statements that allow you to specify the data to display, print, or store Database Management Systems query results Next wizard for querying the database p. 13.16 Fig. 13-14

  30. What is a query by example (QBE)? The program retrieves records that match criteria you enter in the form fields Uses a graphical user interface Database Management Systems query by example screen query results Next p. 13.17 Fig. 13-15

  31. What is a form? Sometimes called a data entry form A window on the screen that provides areas for entering or changing data in a database Database Management Systems Next p. 13. Fig. 13-16

  32. What is an electronic form? Also called an e-form A form that sends entered data across a network or the Internet Typically uses a means to secure the data while it is transported Database Management Systems Next p. 13.18 Fig. 13-17

  33. What is a report generator? Also called a report writer Allows you to design a report on the screen, retrieve data into the report design, and then display or print the report Usually allows you to format page numbers and dates; titles and column headings; subtotals and totals; and fonts, font sizes, color, and shading Database Management Systems Next p. 13. 19Fig. 13-18

  34. A DBMS provides means to make certain only authorized users can access data at permitted times Most DBMSs allow you to identify different levels of access privileges for each field in the database What is data security? Database Management Systems Access privileges Define the activities that a specific user or group of users can perform Read-only privileges User can retrieve data, but cannot change it Full-update privileges User can retrieve and change the data Next Click to view video p. 13.19

  35. How should you protect data stored in a database? A DBMS provides a variety of techniques to restore a database to a usable form in case it is damaged or destroyed Database Management Systems Backup On a regular basis, make a backup, or copy, of the entire database Some DBMSs have their own backup utilities Next p. 13.20

  36. What is a log? A listing of activities that change the contents of the database For every change the DBMS places three items in the log Database Management Systems before image: a copy of the customer record prior to the change after image: a copy of the customer record after the change the actual change of data Next p. 13.20 Fig. 13-18

  37. What is a recovery utility? Uses the logs and/or backups to restore a database when it is damaged or destroyed Restores the database using rollback and rollforward techniques Database Management Systems Rollforward Also called forward recovery The DBMS uses the log to re-enter changes made to the database since the last save or backup Rollback Also called backward recovery The DBMS uses the log to undo any changes made to the database during a certain period of time Next p. 13.20

  38. What is a data model? Every database and DBMS is based on a specific data model Consists of rules and standards that define how the database organizes data Defines how users view the organization of the data Three popular data models in use today Object-relational databases combine features of the relational and object-oriented data models Relational, Object-Oriented and Multidimensional Databases Next Relational Databases Object-oriented Databases Object-relational Databases Click to viewanimation Multidimensional Databases p. 13.21 Fig. 13-20

  39. Oracle products are used by 96 percent of the Fortune 500 companies In 1977, Larry Ellison co-founded Oracle Now the world’s leading supplier of software for e-business Its database product, also named Oracle, is the world’s leading database software Company on the Cutting Edge Next Click to view video Click to view Web Link then click Oracle Corporation p. 13.21

  40. E. F. Codd In 1970, he created the relational approach to database management Codd’s model continues to serve as the de facto standard on which large and small databases are structured Technology Trailblazer Next Click to view Web Link then click E. F. Codd p. 13.22

  41. What is a relational database? Stores data in tables that consist of rows and columns Each row has a primary key and each column has a unique name A relational database uses terms different from a file processing environment Relational, Object-Oriented, and Multidimensional Databases Next Data terminology Click to view Web Link then click Relational Databases p. 13.22 Fig. 13-21

  42. What is a relationship? A connection within the data Relationships stored as part of a relational database Normalization is a process designed to make sure the data within the relations (tables) contains the least amount of duplication Relational, Object-Oriented, and Multidimensional Databases Next row column table relationships p. 13.22 Fig. 13-22

  43. What is relational algebra? Uses variables and operations to build new relations Used to manipulate and retrieve data Variables are the tables, rows, and columns of the database Relational, Object-Oriented, and Multidimensional Databases Projection operation Retrieves data from columns (fields) Selection operation Retrieves data from certain rows (records) Join operation Combines the data from two or more tables Next p. 13.24

  44. What is an example of a projection operation? The operation extracts data from a column (field) Relational, Object-Oriented, and Multidimensional Databases projection operation results Next all rows and columns in Movie table p. 13.24 Fig. 13-23

  45. What is an example of a selection operation? The operation extracts data from a row (record) Relational, Object-Oriented, and Multidimensional Databases selection operation results Next all rows and columns in Movie table p. 13.24 Fig. 13-23

  46. What is an example of a combined projection and selection operation? The operation extracts data from a column (field) Relational, Object-Oriented, and Multidimensional Databases projection and selection operation results Next all rows and columns in Movie table p. 13.24 Fig. 13-23

  47. What is an example of a join operation? Combines the data from two or more tables using a common column Relational, Object-Oriented, and Multidimensional Databases Rental Table Movie Table Rental Table and Movie Table Joined on Movie ID Column Next p. 13.24 Fig. 13-24

  48. What is Structured Query Language (SQL)? A query language that allows you to manage, update, and retrieve data Uses relational algebra Has special keywords and rules that you include in SQL statements Relational, Object-Oriented, and Multidimensional Databases projection operation join operation selection operation Next Click to view Web Link then click SQL p. 13.25 Fig. 13-25

  49. What is an object-oriented database (OODB)? Stores data in objects Advantages Can store more types of data Can access the data faster Relational, Object-Oriented, and Multidimensional Databases Object An item that can contain both data and the activities that read or process the data Object query language (OQL) Query language used to manipulate and retrieve object-oriented and object-relational data Next Click to view Web Link then click Object-Oriented Databases p. 13.26

  50. What are examples of applications appropriate for an OODB? Relational, Object-Oriented, and Multidimensional Databases Multimedia databases Store images, audio clips, and/or video clips Hypertext databases Contain text links to other documents Groupware databases Store documents such as schedules, calendars, manuals, memos, and reports Hypermedia databases Contain text, graphics, video, and sound Computer-aided design (CAD) databases Store data about engineering, architectural, and scientific designs Web databases Link to an e-form on a Web page Next p. 13.26