1 Introduction to Oracle Chapter 1

2 Before Databases Information was kept in files: Each field describes one piece of information about student Fields are separated by commas A record is a collection of related fields Each record is a separate line

3 Problems with Files Proliferation of data management programs to deal with different file formats Redundant data stored in files Data files may contain inconsistent data

4 Database Approach Database stores all organizational data in a central location Good database design eliminates redundant data to reduce the possibility of inconsistent data Single application called the database management system (DBMS) performs all routine data handling operations Database administrator (DBA): person responsible for installing, administering, and maintaining the database

5 Types of database models hierarchical model network model relational model object oriented model.

6 Early Databases – Hierarchical Structure

7 Relational Databases

8 Object-oriented Example Students Courses

9 Relational Database Terms Entity: an object about which you want to store data Relationships: links that show how different records are related Key Fields: establish relationships among records in different tables Five main types of key fields: primary keys candidate keys foreign keys composite keys

10 Primary Keys Primary key Value must be unique for each record Serves to identify the record Present in every record Can’t be NULL Should be numeric

11 Candidate Keys Candidate key Any field that could be used as the primary key Should be a unique, unchanging numeric field

12 Foreign Keys Foreign key: a field in a table that is a primary key in another table Foreign key creates a relationship between the two tables Foreign key value must exist in the table where it is a primary key

13 Composite Keys Composite key: a unique key that you create by combining two or more fields Usually comprised of fields that are primary keys in other tables

14 Client/Server Database Management Systems Client/server database Takes advantage of distributed processing and networked computers by distributing processing across multiple computers DBMS server process runs on one workstation, and the database applications run on separate client workstations across the network Preferred for database applications that retrieve and manipulate small amounts of data from databases containing large numbers of records because they minimize network traffic and improve response times Organizations generally use a client/server database if the database will have more than 10 simultaneous users and if the database is mission critical

15 Client/Server Database Architecture

16 The Oracle Client/Server Database Oracle11i is the latest release of Oracle Corporation’s relational database All Oracle server- and client-side programs use Oracle Net, a utility that enables the network communication between the client and the server

17 Client-Side Utilities SQL*Plus for creating and testing command-line SQL queries and executing PL/SQL procedural programs Oracle10i Developer Suite for developing database applications including the following Developer tools: Forms Builder for creating custom user applications Reports Builder for creating reports for displaying, printing, and distributing summary data Enterprise Manager for performing database administration tasks such as creating new user accounts and configuring how the DBMS stores and manages data

18 Design Principles To avoid creating tables that contain redundant data, group related items that describe a single entity together in a common table Do not create tables that duplicate values many times in different rows When creating a database and inserting data values, you must specify the data type for each column Recall that primary key fields should use a number data type to avoid typographical, punctuation, and case variation errors

19 The Northwoods University Student Registration Database Northwoods University Decided to replace its aging mainframe-based student registration system with a more modern client/server database system School officials want students to be able to retrieve course availability information, register for courses, and print transcripts using personal computers located in the student computer labs

20 The Northwoods University Student Registration Database (cont) Faculty members must be able to retrieve student course lists, drop and add students, and record course grades Faculty members must also be able to view records for the students they advise Security is a prime concern, so student and course records must be protected by password access

21 Northwoods University Data Requirements Student name, address, telephone number, class (freshman, sophomore, junior, or senior), date of birth, PIN (personal identification number), and advisor ID Course call number (such as MIS 101), course name, credits, location, duration, maximum enrollment, instructor, and term offered Instructor name, office location, telephone number, rank, and PIN Student enrollment and grade information

22 Northwoods University Table Relationships