2. Welcome to CMPE003 Personal Computer Concepts: Hardware and Software Winter 2003 UC Santa Cruz Instructor: Guy Cox

3. January 23, 20032 Assignments Assignment #6 – The Last One  Due March 12, 2003 Spreadsheets – (MS Excel)  Generate a monthly budget spreadsheet http://www.soe.ucsc.edu/classes/cmpe003/Winter03/hw6_spreadsheet.htm l

4. January 23, 20033 Final Project Due no later than March 19, 2003  You can turn in earlier.. Power Point presentation  4 pages  Extra points for special effects, animations Turn in on a floppy/CDROM http://www.soe.ucsc.edu/classes/cmpe003/Winter03/finalproject.html

5. Database Management: Getting Data Together Chapter 14

6. January 23, 20035 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. January 23, 20036 Computer Databases Track information Allows higher productivity as a result of better information

8. January 23, 20037 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. January 23, 20038 Hierarchy of Data

10. January 23, 20039 File Processing File processing  Data redundancy Database models reduce redundancy  Saves storage space  Saves update effort Time Accuracy

11. January 23, 200310 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. January 23, 200311 Data: Getting Organized Character Field Record File Database

13. January 23, 200312 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. January 23, 200313 Sequential Records are stored and accessed in order All records prior to the one requested must be read Magnetic tape storage

15. January 23, 200314 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. January 23, 200315 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. January 23, 200316 Processing Stored Data Batch Transaction Terminology  Transaction – updates a record  Master file – contains all the data

18. January 23, 200317 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. January 23, 200318 Batch Processing Stored Data

20. January 23, 200319 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. January 23, 200320 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. January 23, 200321 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. January 23, 200322 Database Models Database Types  Relational  Object-oriented  Hierarchical  Network Each type structures, organizes and uses data differently

24. January 23, 200323 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. January 23, 200324 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. January 23, 200325 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. January 23, 200326 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. January 23, 200327 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. January 23, 200328 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. January 23, 200329 DBMS: Database Management System Basic functions Create a database Enter data Modify the data as required Retrieve information from the database

31. January 23, 200330 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. January 23, 200331 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. January 23, 200332 DBMS: Data Retrieval Extracting the desired data from the database Primary forms  Queries  Reports

34. January 23, 200333 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. January 23, 200334 Query SQL Structured Query Language Entered directly by user Included in programs QBE Query-by-Example Graphical interface to specify your criteria

36. January 23, 200335 Report Formatted presentation of data from the database Normally printed Designed using a report generator

37. January 23, 200336 The DBMS Process Enter the data Review the data and edit until accurate Describe the data

38. January 23, 200337 The DBMS Process The Plan… The Report…

39. January 23, 200338 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. January 23, 200339 Concurrency Control

41. January 23, 200340 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. January 23, 200341 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. January 23, 200342 Looking at the Data: OLTP – Online Transaction Processing Supports day-to-day database activities Little support for data analysis

44. January 23, 200343 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. January 23, 200344 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. January 23, 200345