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CHAPTER 1: Introduction to Client/Server Databases 1 A GUIDE TO ORACLE8 1 File-Based Approach to Data Processing Checking Account Data Files Checking Account Programs Figure 1-1 Auto Loan Data Files 1 Savings Account Data Files Auto Loan Programs Savings Account Programs 2 Problems with Data File Approach Redundant programs Duplicate data Inconsistent data 1 3 Database Approach to Data Processing Checking Account Programs Organizational Database Database Management System Auto Loan Programs Figure 1-2 Savings Account Programsh 1 4 Personal Databases Single user’s desktop computer DBMS and Client Database applications are stored on user’s workstation All files are transmitted across network 1 5 Personal Database Structure File Server 1. “Listens” for file requests. 2. Sends and receives files. Figure 1-3 Network File Requests Updated Files 1 Requested Files File Requests Updated Files Requested Files User 1 Client Workstation (DBMS Application & Client DB Applications) User 2 Client Workstation (DBMS Application & Client DB Applications) 1. Send file requests. 2. Receives files. 3. Filter data from files and/or 4. Add new data to files. 1. Send file requests. 2. Receives files. 3. Filter data from files and/or 4. Add new data to files. 6 Client/Server Databases DBMS process runs on server Client applications run on user’s workstation Data requests are transmitted to DBMS DBMS only returns filtered data 1 7 Client/Server Database Structure 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. Figure 1-4 Network Data Request. Data input/update 1 Filtered Data Filtered Data Data Request. Data Input/Update. User 1 Client Workstation (Client DB Application) User 2 Client Workstation (Client DB Application) 1. Send data request. 2. Receive filtered data. or 3. Send data input or update. 1. Send data request. 2. Receive filtered data. or 3. Send data input or update. 8 Other Advantages of Client/Server Databases Handling server and client failures Processing transactions Handling high data volumes Providing security Servicing multiple simultaneous users 1 9 The Oracle8 Environment SQL*Plus PL/SQL Developer 1 Procedure Builder Query Builder Form Builder Report Builder Graphics Builder Project Builder Oracle Application Server (Web pages) 10 Overview of Databases Hierarchical Parent-to-child relationships Relationships maintained using pointers Relational Data stored in tables Relationships created through shared key fields 1 11 Hierarchical Database 1 Figure 1-5 12 Relational Database Terms Table: Matrix with columns and rows Column: Data category Also called fields Row: Contains actual data values Also called records 1 13 Relational Database With Two Tables 1 Figure 1-6 14 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 key 1 Value must be a primary key in another table Used to create a relationship 15 Creating a Relationship With a Foreign Key 1 Figure 1-7 16 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 1 17 Example of a Composite Primary Key Figure 1-8 1 18 Case Study Databases Clearwater Traders Mail-order clothing and sporting goods retailer Northwoods University University registration system 1 19 Clearwater Traders Tables CUSTOMER CUST_ORDER ITEM INVENTORY SHIPPING 1 BACKORDER ORDERLINE COLOR ORDERSOURCE 20 Lookup Tables Lookup table: List of legal values for a field COLOR ORDERSOURCE 1 21 Northwoods University Tables STUDENT FACULTY LOCATION TERM COURSE 1 COURSE_SECTION ENROLLMENT 22