1

A GUIDE TO

ORACLE8

CHAPTERCHAPTER 1:1:IntroductionIntroductionto Client/Server to Client/Server DatabasesDatabases

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CheckingAccount

DataFiles

AutoLoanDataFiles

SavingsAccount

DataFiles

File-Based Approach to Data Processing

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CheckingAccount

Programs

AutoLoan

Programs

SavingsAccount

Programs

Figure 1-1

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Problems with Data File Approach

Redundant programsDuplicate dataInconsistent data

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Database Approach to Data Processing

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OrganizationalDatabase

DatabaseManagement

System

CheckingAccount

Programs

AutoLoan

Programs

SavingsAccount

Programsh

Figure 1-2

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Personal Databases

Single user’s desktop computerDBMS and Client Database

applications are stored on user’s workstation

All files are transmitted across network

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Personal Database Structure

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File RequestsUpdated Files

Requested Files

Network

User 1 Client Workstation(DBMS Application & Client DB Applications)1. Send file requests. 2. Receives files.3. Filter data from files and/or4. Add new data to files.

Requested FilesFile RequestsUpdated Files

File Server1. “Listens” for file requests.2. Sends and receives files.

User 2 Client Workstation(DBMS Application & Client DB Applications)1. Send file requests. 2. Receives files.3. Filter data from files and/or4. Add new data to files.

Figure 1-3

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Client/Server Databases

DBMS process runs on serverClient applications run on user’s

workstationData requests are transmitted to

DBMSDBMS only returns filtered data

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Client/Server Database Structure

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Network

Database Server (DBMS Process)1. “Listens” for data requests, new data, and updates.2. Filters requested data from the database and sends it to client.

User 1 Client Workstation(Client DB Application)1. Send data request. 2. Receive filtered data.or3. Send data input or update.

User 2 Client Workstation(Client DB Application)1. Send data request. 2. Receive filtered data.or3. Send data input or update.

Filtered Data Filtered DataData Request.Data Input/Update.

Data Request.Data input/update

Figure 1-4

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Other Advantages of Client/Server Databases

Handling server and client failuresProcessing transactionsHandling high data volumes Providing securityServicing multiple simultaneous users

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The Oracle8 Environment

SQL*Plus PL/SQL Developer

Procedure BuilderQuery BuilderForm BuilderReport BuilderGraphics BuilderProject Builder

Oracle Application Server (Web pages)11

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Overview of Databases

HierarchicalParent-to-child relationshipsRelationships maintained using pointers

RelationalData stored in tablesRelationships created through shared

key fields

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Hierarchical Database

11 Figure 1-5

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Relational Database Terms

Table: Matrix with columns and rowsColumn: Data category

Also called fields

Row: Contains actual data valuesAlso called records

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Relational Database With Two Tables

11Figure 1-6

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Relational Database Terms

Primary key: Field whose value must be unique for each record

Candidate key: Field that could be used for primary key

Foreign keyValue must be a primary key in another

tableUsed to create a relationship11

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Creating a Relationship With a Foreign Key

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Relational Database Terms

Composite key: Primary key created using multiple fields

Surrogate key: Numerical value generated by the database for use as a primary key

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Example of a Composite Primary Key

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Case Study Databases

Clearwater TradersMail-order clothing and sporting goods

retailer

Northwoods UniversityUniversity registration system

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Clearwater Traders Tables

CUSTOMER CUST_ORDER ITEM INVENTORY SHIPPING

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BACKORDER ORDERLINE COLOR ORDERSOURCE

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Lookup Tables

Lookup table: List of legal values for a fieldCOLORORDERSOURCE

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Northwoods University Tables

STUDENT FACULTY LOCATION TERM COURSE

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COURSE_SECTION ENROLLMENT