L23 ch14

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Welcome to CMPE003 Personal Computers: Hardware and Software: 

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

Exams: 

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

Assignments: 

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

Database Management: Getting Data Together: 

Database Management: Getting Data Together Chapter 14

Objectives: 

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

Computer Databases: 

Computer Databases Track information Allows higher productivity as a result of better information

Hierarchy of Data: 

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

Hierarchy of Data: 

Hierarchy of Data

File Processing: 

File Processing File processing Data redundancy Database models reduce redundancy Saves storage space Saves update effort Time Accuracy

Data (From Chapter 6) Organizing and Accessing: 

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

Data Getting Organized: 

Data Getting Organized Character Field Record File Database

Data Access Methods: 

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

Sequential: 

Sequential Records are stored and accessed in order All records prior to the one requested must be read Magnetic tape storage

Direct / Random Access: 

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

Indexed: 

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

Processing Stored Data: 

Processing Stored Data Batch Transaction Terminology Transaction – updates a record Master file – contains all the data

Batch Processing: 

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

Batch Processing Stored Data: 

Batch Processing Stored Data

Transaction Processing: 

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

Batch and Transaction: 

Batch and Transaction Computer system may use both processing types based upon the application Transaction Activities relating to current needs Batch Updates per schedule

Applications: 

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

Database Models: 

Database Models Database Types Relational Object-oriented Hierarchical Network Each type structures, organizes and uses data differently

RDBMS Relational Database Management System: 

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)

RDBMS Key: 

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

OODBMS Object-Oriented Database Management System: 

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

OODBMS Object-Oriented Database Management System: 

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

Data Integrity: 

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)

DBMS Database Management System: 

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

DBMS Database Management System: 

DBMS Database Management System Basic functions Create a database Enter data Modify the data as required Retrieve information from the database

DBMS Create a Database: 

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

DBMS Enter and Modify Data: 

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

DBMS Data Retrieval: 

DBMS Data Retrieval Extracting the desired data from the database Primary forms Queries Reports

Query: 

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

Query: 

Query SQL Structured Query Language Entered directly by user Included in programs QBE Query-by-Example Graphical interface to specify your criteria

Report: 

Report Formatted presentation of data from the database Normally printed Designed using a report generator

The DBMS Process: 

The DBMS Process Enter the data Review the data and edit until accurate Describe the data

The DBMS Process: 

The DBMS Process The Plan… The Report…

Concurrency Control: 

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

Concurrency Control: 

Concurrency Control

Security: 

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

Backup and Recovery: 

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

Looking at the Data OLTP – Online Transaction Processing: 

Looking at the Data OLTP – Online Transaction Processing Supports day-to-day database activities Little support for data analysis

Looking at the Data Data Warehouses: 

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

Looking at the Data Data Warehouses: 

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

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