2. Welcome to CMPE003 Personal Computers: Hardware and Software Dr. Chane Fullmer Fall 2002 UC Santa Cruz

3. November 18, 20022 Exams Exams now on-line….. http://www.cse.ucsc.edu/classes/cmpe003/Fall02/ Must have your own Scantron form to determine test version you took

4. November 18, 20023 Assignments Assignment #6 – The Last One Due November 22, 2002 This Friday…don’t be late.. Using Spreadsheets – (M$ Excel) Generate a personal monthly budget spreadsheet Must printout in color if you use color for the conditional in part #10 http://www.soe.ucsc.edu/classes/cmpe003/Fall02/hw6_spreadsheet.html

5. Database Management: Getting Data Together Chapter 14

6. November 18, 20025 Objectives Describe the hierarchy of data Explain the differences between files and databases List the four database models Describe the concept of data integrity Describe the functions of a database management system Describe the process of creating a database in general terms Compare and contrast relational and object-oriented databases Explain what a data warehouse is an how it differs from a database

7. November 18, 20026 Computer Databases Track information Allows higher productivity as a result of better information

8. November 18, 20027 Hierarchy of Data Field Smallest meaningful unit of data Group of one or more characters that has a specific meaning Used as “key” to locate records Record Set of fields containing all information known about one entity Each record contains the same fields in the same sequence File Collection of related records

9. November 18, 20028 Hierarchy of Data

10. November 18, 20029 File Processing File processing Data redundancy Database models reduce redundancy Saves storage space Saves update effort Time Accuracy

11. November 18, 200210 Data (From Chapter 6) Organizing and Accessing Design (plan) for way data is Received Organized Stored how it will be processed Plan determined by programmer and/or systems analyst

12. November 18, 200211 Data Getting Organized Character Field Record File Database

13. November 18, 200212 Data Access Methods Application determines how data must be accessed by users Data is organized based upon access method Organization method limits choice of storage medium

14. November 18, 200213 Sequential Records are stored and accessed in order All records prior to the one requested must be read Magnetic tape storage

15. November 18, 200214 Direct / Random Access Records are not physically stored in any order Go directly to the record to read Hashing – apply a formula to the key to produce the address of the record Collision – same address from different keys Updating in place Read, change, and return a record to the same place on disk DASD – Direct-Access Storage Device needed ie, Disk Drive

16. November 18, 200215 Indexed Records are stored sequentially Index is generated that contains key and address Can be read in order = sequential Can be read out of order = random

17. November 18, 200216 Processing Stored Data Batch Transaction Terminology Transaction – updates a record Master file – contains all the data

18. November 18, 200217 Batch Processing Collect transactions into a transaction file and perform periodic updates Process Transactions are sorted by key field Computer matches the master and transaction keys Performs requested action – add, revise, delete New master file created Error report is printed Master file only current immediately after processing

19. November 18, 200218 Batch Processing Stored Data

20. November 18, 200219 Transaction Processing Processed upon request Real-time – process handled immediately Disk storage Direct access to desired record needed Immediate access to stored data Immediate updating of stored data

21. November 18, 200220 Batch and Transaction Computer system may use both processing types based upon the application Transaction Activities relating to current needs Batch Updates per schedule

22. November 18, 200221 Applications Motor Vehicle Dept Transaction Police check for stolen car report Batch Motor vehicle records of owner information Retail – POS Transaction Item price Inventory updates as sale is made Batch Produce daily and weekly sales reports Banks Transaction Check balance Record cash withdrawal Batch Deposit left in the deposit drop Bank statement

23. November 18, 200222 Database Models Database Types Relational Object-oriented Hierarchical Network Each type structures, organizes and uses data differently

24. November 18, 200223 RDBMS Relational Database Management System Organizes data into related tables (files) Table consists of rows and columns Tables linked based upon a common field (key)

25. November 18, 200224 RDBMS Key Primary key A field whose value uniquely identifies a record Foreign key Primary key of another table Used as link to other table May have duplicate values

26. November 18, 200225 OODBMS Object-Oriented Database Management System Manipulates object-oriented databases Object – represents a real-world entity Attributes / properties Data about the entity Methods / Actions Operations that work the data

27. November 18, 200226 OODBMS Object-Oriented Database Management System Compared to RDBMS More complex Steeper learning curve Skilled employees needed who earn high pay Combined Object/relational DBMS Relational database that incorporates some complex data types

28. November 18, 200227 Data Integrity Degree to which data is accurate and reliable Integrity constraints – rules Acceptable values for a field Primary key values Foreign keys Integrity constraints must be enforced when data is entered or data is unreliable GIGO (Garbage in, garbage out)

29. November 18, 200228 DBMS Database Management System Levels of software Sophisticated Mainframe Expensive – tens of thousands of dollars Complex Planned and managed by computer professionals Simple PC Inexpensive – few hundred dollars User can set up and use the database

30. November 18, 200229 DBMS Database Management System Basic functions Create a database Enter data Modify the data as required Retrieve information from the database

31. November 18, 200230 DBMS Create a Database Data Dictionary / Catalog Stored data about the tables and fields within the database Per table Table name Relationships Per field Field name Data type Field size Validation rules

32. November 18, 200231 DBMS Enter and Modify Data Operations Adding new data Modifying data Deleting data Methods User interacts directly with DBMS Programs written by professional programmers access the data using special commands built into the DBMS

33. November 18, 200232 DBMS Data Retrieval Extracting the desired data from the database Primary forms Queries Reports

34. November 18, 200233 Query Ask a question about the data Present criteria that selects data from the database Results in smaller portion of the database Query Language Prepare your query using English-like statements Proprietary query language in DBMS

35. November 18, 200234 Query SQL Structured Query Language Entered directly by user Included in programs QBE Query-by-Example Graphical interface to specify your criteria

36. November 18, 200235 Report Formatted presentation of data from the database Normally printed Designed using a report generator

37. November 18, 200236 The DBMS Process Enter the data Review the data and edit until accurate Describe the data

38. November 18, 200237 The DBMS Process The Plan… The Report…

39. November 18, 200238 Concurrency Control Databases are used concurrently by many users Problem if several users attempt to update the same record at the same time Record locking First user requests record Others are locked out for update

40. November 18, 200239 Concurrency Control

41. November 18, 200240 Security Data is stored in a central location Problem: unauthorized access is major concern Benefit: easier to apply security measures Features User ID and password Privileges assigned to each user Read-only Update

42. November 18, 200241 Backup and Recovery Why? Data can be accidentally damaged or destroyed Hardware can fail Forces of nature can cause physical damage Software or human errors can corrupt data Backup – copy made periodically Recovery – replaces the damaged database with the good backup

43. November 18, 200242 Looking at the Data OLTP – Online Transaction Processing Supports day-to-day database activities Little support for data analysis

44. November 18, 200243 Looking at the Data Data Warehouses Databases designed to support ongoing operations Data is captured from the db over time Summary form Scheduled basis Period of time May include data from external sources

45. November 18, 200244 Looking at the Data Data Warehouses Online Analytical Processing (OLAP) Analyzes the data Produces information for managers Data mining Statistical and artificial intelligence techniques Look for otherwise unrecognized -- Patterns Relationships Correlations Trends Helps managers make strategic business decisions

46. November 18, 200245