SQL and PL/SQL Using Procedure Buider

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder... Introduction to Oracle: SQL and PL/SQL Using Procedure Builder xivProfile Before You Begin This Course Before you begin

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder

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Volume 1

Preface xi

Profile xii

Related Publications xviii

Typographic Conventions xix

I Introduction IĆ1 Course Objectives IĆ3 Course Outline IĆ5 The Relational Database Concept IĆ9 System Development Cycle IĆ17 What Is Oracle? IĆ19 The Oracle Product Set IĆ21 SQL, SQL*Plus, and PL/SQL IĆ23 Summit Sporting Goods Demonstration Tables IĆ29 Summary IĆ33

1 Selecting Rows 1Ć1 Objectives 1Ć3 The Basic Query Block 1Ć5 Arithmetic Expressions 1Ć13 Column Aliases 1Ć21 The Concatenation Operator 1Ć23 Literal Character String 1Ć25 Managing Null Values 1Ć27 Preventing the Selection of Duplicate Rows 1Ć31 SQL*Plus Commands 1Ć35 Logging in to SQL*Plus 1Ć37 Displaying Table Structure 1Ć39 SQL*Plus Editing Commands 1Ć41 SQL*Plus File Commands and Online Help 1Ć43

Negating Expressions 2Ć17 SQL Operators 2Ć19 Querying Data with Multiple Conditions 2Ć27 Rules of Precedence 2Ć29 Summary 2Ć33 Practice Overview 2Ć35 Practice 2 2Ć37

3 Single Row Functions 3Ć1 Objectives 3Ć3 Overview 3Ć5 Single Row Functions 3Ć7 Character Functions 3Ć9 Number Functions 3Ć17 Oracle Date Format 3Ć23 Using Arithmetic Operators with Dates 3Ć25 Date Functions 3Ć27 Conversion Functions 3Ć33 TO_CHAR Function with Date Formats 3Ć35 TO_CHAR Function with Number Formats 3Ć45 TO_NUMBER and TO_DATE Functions 3Ć49 Nesting Single Row Functions 3Ć51 Nesting Functions 3Ć53 Summary 3Ć55 Practice Overview 3Ć57 Practice 3 3Ć59

4 Displaying Data from Multiple Tables 4Ć1 Objectives 4Ć3 Overview 4Ć5 What Is a Cartesian Product? 4Ć7 Simple Join Query 4Ć9 Using Table Aliases 4Ć17 NonĆEquijoin 4Ć19 Returning Records with No Direct Match 4Ć21 Joining a Table to Itself 4Ć25 Summary 4Ć27 Practice Overview 4Ć29 Practice 4 4Ć31

5 Group Functions 5Ć1 Objectives 5Ć3 Overview 5Ć5 Group Functions 5Ć7

The GROUP BY Clause 5Ć13 Illegal Queries Using Group Functions 5Ć19 Groups Within Groups 5Ć23 The HAVING Clause 5Ć25 Summary 5Ć31 Practice Overview 5Ć33 Practice 5 5Ć34

6 Subqueries 6Ć1 Objectives 6Ć3 Overview 6Ć5 Subqueries 6Ć7 How Are Nested Subqueries Processed? 6Ć9 Single Row Subqueries 6Ć11 Errors with Subqueries 6Ć15 Multiple Row Subqueries 6Ć17 HAVING Clause with Nested Subqueries 6Ć19 Summary 6Ć21 Practice Overview 6Ć23 Practice 6 6Ć25Volume 2

7 Specifying Variables at Runtime 7Ć1 Objectives 7Ć3 Overview 7Ć5 Substitution Variables 7Ć7 Single Ampersand Substitution Variables 7Ć9 Defining User Variables 7Ć15 Passing Values into a Script File 7Ć21 Summary 7Ć23 Practice Overview 7Ć25 Practice 7 7Ć26

8 Overview of Data Modeling and Database Design 8Ć1

9 Creating Tables 9Ć1 Objectives 9Ć3 Overview 9Ć5 Creating Tables 9Ć7 Oracle7 Datatypes 9Ć13 Constraints 9Ć15 Creating a Table from a Table Instance Chart 9Ć25 Creating a Table from Rows in Another Table 9Ć31 Confirming Table Creation 9Ć33 Summary 9Ć35 Practice Overview 9Ć37 Practice 9 9Ć39

10 Oracle Data Dictionary 10Ć1 Objectives 10Ć3 Overview 10Ć5 Querying the Data Dictionary 10Ć7 Checking Constraints on a Table 10Ć13 Summary 10Ć17 Practice Overview 10Ć19 Practice 10 10Ć21

11 Manipulating Data 11Ć1 Objectives 11Ć3 Overview 11Ć5 Adding a New Row to a Table 11Ć7 Copying Rows from Another Table 11Ć19 Updating Rows 11Ć21 Deleting Rows 11Ć29 Transaction Processing 11Ć35 Committing Changes 11Ć39 Rolling Back Changes 11Ć43 Rolling Back Changes to a Savepoint 11Ć45 Statement Level Rollback 11Ć47 Summary 11Ć49 Practice Overview 11Ć51 Practice 11 11Ć53

12 Altering Tables and Constraints 12Ć1 Objectives 12Ć3 Overview 12Ć5 Adding a Column 12Ć7 Modifying a Column 12Ć9 Adding and Dropping a Constraint 12Ć11

Disabling and Enabling a Constraint 12Ć15 Dropping a Table 12Ć17 Renaming and Truncating a Table 12Ć19 Adding a Comment to a Table 12Ć21 Summary 12Ć23 Practice Overview 12Ć25 Practice 12 12Ć27

13 Creating Sequences 13Ć1 Objectives 13Ć3 Overview 13Ć5 Creating a Sequence 13Ć7 Using a Sequence 13Ć13 Altering a Sequence 13Ć17 Removing a Sequence 13Ć19 Summary 13Ć21 Practice Overview 13Ć23 Practice 13 13Ć25

14 Creating Views 14Ć1 Objectives 14Ć3 Overview 14Ć5 Creating a View 14Ć7 Performing DML Operations on a View 14Ć15 Confirming View Names and Structures 14Ć21 Removing a View 14Ć23 Summary 14Ć25 Practice Overview 14Ć27 Practice 14 14Ć29

15 Creating Indexes 15Ć1 Objectives 15Ć3 Overview 15Ć5 When Is the Index Used? 15Ć7 Index Structure 15Ć9

System Privileges 16Ć7 What Is a Role? 16Ć11 Changing Your Password 16Ć13 Granting Object Privileges 16Ć15 Confirming Privileges Granted 16Ć21 Revoking Object Privileges 16Ć23 Creating a Synonym for an Object 16Ć25 Summary 16Ć29 Practice Overview 16Ć31 Practice 16 16Ć33

17 Summary of SQL and SQL*Plus 17Ć1 Summary of SQL and SQL*Plus 17Ć3 Practice Overview 17Ć9 Practice 17 17Ć11Volume 3

18 Overview of PL/SQL 18Ć1 Objectives 18Ć3 Overview 18Ć5 PL/SQL Block Structure 18Ć9 The PL/SQL Environment 18Ć15 About Procedure Builder 18Ć17

19 Basics of Procedure Builder 19Ć1 Objectives 19Ć3 Overview 19Ć5 Oracle Procedure Builder Capabilities 19Ć7 Procedure Builder Components 19Ć9 The Object Navigator 19Ć15 The Interpreter 19Ć23 The Program Unit Editor 19Ć27 The Stored Program Unit Editor 19Ć31 Debugging a Stored Program Unit 19Ć33 Performing Debug Actions in the Interpreter 19Ć35 Setting a Breakpoint 19Ć37 Examining Local Variables 19Ć43 Summary 19Ć45 Practice Overview 19Ć47 Practice 19 19Ć49

20 Modularizing Programming with Subprograms 20Ć1 Objectives 20Ć3 Overview 20Ć5

Creating a Subprogram 20Ć7 Creating a Procedure 20Ć9 Comparing Functions and Procedures 20Ć15 Creating a Function 20Ć17 Invoking Subprograms 20Ć21 Summary 20Ć29 Practice Overview 20Ć31 Practice 20 20Ć33

21 Developing a Simple PL/SQL Block 21Ć1 Objectives 21Ć3 Overview 21Ć5 Declaring PL/SQL Variables and Constants 21Ć7 Declaring Scalar Variables 21Ć9 Declaring Composite Datatypes 21Ć15 PL/SQL Block Syntax Rules 21Ć25 Assigning Values to Variables 21Ć29 Programming Guidelines 21Ć43 Summary 21Ć49 Practice Overview 21Ć51 Practice 21 21Ć53

22 Interacting with Oracle 22Ć1 Objectives 22Ć3 Overview 22Ć5 Retrieving Data Using PL/SQL 22Ć7 SELECT Exceptions 22Ć15 Manipulating Data Using PL/SQL 22Ć19 SQL Cursor 22Ć23 Controlling Transactions 22Ć27 Summary 22Ć31 Practice Overview 22Ć33 Practice 22 22Ć35

23 Controlling Flow in PL/SQL Blocks 23Ć1

24 Processing Queries by Using Explicit Cursors 24Ć1 Objectives 24Ć3 Overview 24Ć5 Controlling Explicit Cursors 24Ć7 Explicit Cursor Attributes 24Ć17 Cursors and Records 24Ć21 Cursors with Parameters 24Ć23 Cursor FOR Loops 24Ć25 Applying the WHERE CURRENT OF Clause 24Ć27 Summary 24Ć29 Practice Overview 24Ć31 Practice 24 24Ć33

25 Error Handling 25Ć1 Objectives 25Ć3 Overview 25Ć5 Exception Types 25Ć7 Trapping Exceptions 25Ć9 Trapping Predefined Oracle7 Server Exceptions 25Ć11 Trapping NonĆPredefined Oracle7 Server Exceptions 25Ć15 Trapping UserĆDefined Exceptions 25Ć17 Error Trapping Functions 25Ć19 Propagating Exceptions 25Ć21 Summary 25Ć23 Practice Overview 25Ć25 Practice 25 25Ć27

26 Summary of PL/SQL 26Ć1 Summary 26Ć3 Practice Overview 26Ć9 Practice 26 26Ć11Volume 4

A Practice Solutions AĆ1 Preface AĆ3 Practice 1 Solutions AĆ4 Practice 2 Solutions AĆ8 Practice 3 Solutions AĆ20 Practice 4 Solutions AĆ29 Practice 5 Solutions AĆ39 Practice 6 Solutions AĆ46 Practice 7 Solutions AĆ55 Practice 9 Solutions AĆ59 Practice 10 Solutions AĆ63

Practice 11 Solutions AĆ68 Practice 12 Solutions AĆ82 Practice 13 Solutions AĆ88 Practice 14 Solutions AĆ97 Practice 15 Solutions AĆ105 Practice 16 Solutions AĆ109 Practice 17 Solutions AĆ116 Practice 19 Solutions AĆ154 Practice 20 Solutions AĆ155 Practice 21 Solutions AĆ158 Practice 22 Solutions AĆ163 Practice 23 Solutions AĆ170 Practice 24 Solutions AĆ177 Practice 25 Solutions AĆ186 Practice 26 Solutions AĆ192

B Table Descriptions and Data BĆ1 Summit Sporting Goods Database Diagram BĆ3 S_CUSTOMER Table BĆ4 S_DEPT Table BĆ7 S_EMP Table BĆ8 S_IMAGE Table BĆ10 S_INVENTORY Table BĆ11 S_ITEM Table BĆ16 S_ORDTable BĆ20 S_PRODUCT Table BĆ22 S_REGION Table BĆ25 S_WAREHOUSE Table BĆ26

C Using SQL*Plus to Create Reports and Manage PL/SQL Code CĆ1 Objectives CĆ3 Overview CĆ5 Entering Commands in SQL*Plus CĆ7 Comparison of SQL and SQL*Plus Commands CĆ9

Practice C CĆ45 Practice C Solutions CĆ47

D Related Products and Services DĆ1 Related Products DĆ3 Related Services DĆ5 Glossary

Index

Preface

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder xiv

Profile

Before You Begin This Course

Before you begin this course, you should be able to use a graphical user interface(GUI) Required prerequisites are familiarity with data processing concepts andtechniques

HowThis Course Is Organized

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder is an

instructor-led course featuring lecture and hands-on exercises The concepts and skillsintroduced are reinforced by online demonstrations and written practice sessions.HowThis Book Is Organized

Lesson 1: Selecting Rows In order to extract data from the database

you need to use the Structured QueryLanguage (SQL) SELECT command You will want to create SELECTstatements that you can use time andtime again You will also see how to saveyour statements for later use

Lesson 2: Limiting Selected Rows This lesson will cover how to restrict the

rows and columns that are displayed, aswell as how to specify the order in whichthe rows are presented

Profile continued

Lesson 3: Single Row Functions Functions make the basic query block

more powerful and are used tomanipulate data values This is the first

of two lessons that explore functions.You will focus on single row character,number, and date functions, as well asthose functions that convert data fromone type to another, for example,character data to numeric

Lesson 4: Displaying Data from Multiple

Tables

This lesson will cover how to obtain datafrom more than one table, using themany different methods available

Lesson 5: Group Functions This lesson further addresses functions

You will focus on obtaining summaryinformation, such as averages, for groups

of rows You will discuss how to grouprows in a table into smaller sets, and how

to specify search criteria for groups ofrows

Lesson 6: Subqueries This lesson covers more advanced

features of the SELECT statement Youcan write subqueries in the WHEREclause of another SQL statement toobtain values based on an unknownconditional value

Lesson 7: Specifying Variables at

Runtime

You can create a command filecontaining a WHERE clause to restrictthe rows displayed To change thecondition each time the command file isrun, you use substitution variables

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder xvi

Lesson 8: Overview of Data Modeling

and Database Design

Before you build your tables, you designyour database You examine the datamodeling process and relational databaseconcepts, and define normalization Youalso translate an entity relationshipmodel into a relational database design.Lesson 9: Creating Tables You will create tables You will also

build integrity constraints, which arerules governing what can and cannot bedone with the data

Lesson 10: Oracle Data Dictionary The Oracle data dictionary is one of the

most important components of theOracle7 Server It consists of a set oftables and views that provide a read-onlyreference to the database

Lesson 11: Manipulating Data Once your tables have been created, you

will need to add new rows, makechanges to rows in a table, or delete rows

by using data manipulation commands.This lesson covers using SQL commands

to make changes to data A number ofthese data manipulation commands make

up a transaction, which you may eithersave or delete using transaction controls.Lesson 12: Altering Tables and

Constraints

After you create your tables, you mayneed to change the table structuresbecause you omitted a column, yourcolumn definition needs to be changed,

or you want to enable or disableconstraints This lesson will demonstratehow you can amend table structures aswell as add and remove constraints

Profile continued

Lesson 13: Creating Sequences Many applications require the use of

unique numbers as primary key values.You can either build code into theapplication to handle this requirement oruse a sequence to generate uniquenumbers This lesson covers creating andusing sequences that crate unique

numbers

Lesson 14: Creating Views In this lesson, you will see how views

can be used to present data to users in avariety of ways In addition, you will seehow integrity constraints can be

enforced, if using a view to insert,update, or delete data

Lesson 15: Creating Indexes If you want to improve the performance

of some queries, you should considercreating an index You can also useindexes to enforce uniqueness on acolumn or a collection of columns

Lesson 16: Controlling User Access This lesson describes the Oracle7 Server

decentralized security system Using thecommands covered in this lesson, youcan control database access to specificobjects and add new users with differentlevels of access privileges You canprovide alternative names for objects byusing the CREATE SYNONYM

command

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder xviii

Lesson 18: Overview of PL/SQL Overview lesson of how to create and

use PL/SQL program units andsubprograms using Oracle ProcedureBuilder

Lesson 19: Basics of Procedure Builder A key feature of procedural

programming is the ability to create anddebug code quickly and easily

Procedure Builder provides all of thefunctionality necessary for you tosuccessfully develop and debug PL/SQLprograms This lesson enables you tomanipulate PL/SQL code usingProcedure Builder

Lesson 20: Modularizing Programming

with Subprograms

Modularity allows you to break yourcode into manageable, well-definedunits Each of these units in PL/SQL hastwo types of subprograms called

procedures and functions You will learnthe structure of subprograms and how toinvoke them

Lesson 21: Developing a Simple

PL/SQL Block

Create a simple PL/SQL block afterlearning the various elements thatcompose a block

Lesson 22: Interacting with Oracle Access the database and control

transactions through SQL statements inPL/SQL

Profile continued

Lesson 23: Using Control Structures Control the flow of your PL/SQL block

by using conditional statements andloops

Lesson 24: Processing Queries with

Explicit Cursors

Use a multiple row SELECT statementwithin PL/SQL to process many rows.Declare and control explicit cursors,which are used in loops, including thecursor FOR loop

Lesson 25: Error Handling When you execute PL/SQL code, you

may encounter errors The error causesthe PL/SQL block to halt with anexception You can trap the exceptionand perform actions conditionally usingexception handlers

Lesson 26: Summary of PL/SQL

(optional)

Review the topics covered in the course.Create a PL/SQL-based application formanipulating and maintaining

information in your database

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder xx

Related Publications

Oracle Publications

Oracle7 Server SQL Reference, Release 7.3 A32538

SQL*Plus User’s Guide and Reference, Release 3.3 A42562–1

PL/SQL User’s Guide and Reference, Release 2.3 A32542

Oracle7 Server SQL Language Quick Reference 5421–70–1292

SQL*Plus Quick Reference, Release 3.3 A42561

Oracle Procedure Builder 1.5 Developer’s Guide A32485

Oracle7 Server Concepts Manual, Release 7.3 A32534

Oracle Press: Oracle Beginner’s Guide A31178–1

Oracle Press: Oracle Complete Reference A10197–1

Additional References

D System Release Bulletins

D Installation and User’s Guides

D read.me Files

D International Oracle User’s Group (IOUG) Articles

D Oracle Magazine

Typographic Conventions

Typographic Conventions Within Text

Convention Object or Term Example

Uppercase Commands,

functions,column names,table names,PL/SQL objects,schemas

Use the SELECT command to viewinformation stored in the LAST_NAMEcolumn of the S_EMP table

Lowercase,

italic

File names,syntax variables,usernames,passwords

where: role is the name of the role to be

Press the Cancel button

Italic Books, names of

courses andmanuals, andemphasizedwords or phrases

For further information on the subject see:

Oracle7 Server SQL Language Reference Manual

Do not save changes to the database.

Quotation marks Lesson module

titles referencedwithin a course

This subject is covered in Lesson 3, “Workingwith Objects.”

Italic bold The first time a

glossary word isreferred to in asection

The algorithm inserts the new key.

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder xxii

Typographic Conventions Within Code

Convention Object or Term Example

Syntax variables SQL> CREATE ROLE role;

Lowercase Column names,

table names, filenames, PL/SQLobjects

OG_ACTIVATE_LAYER (OG_GET_LAYER (’prod_pie_layer’))

SQL> SELECT userid

Vertical bar Separates

alternativesyntax elements

{OFF | ON}

Underlining Default value in

syntax

{OFF | ON}

Typographic Conventions continuedSymbols Used in This Document

Guidance relating to the subject matter, such as hints or advice

For more information, see

a publication related to the subject matter

This icon indicates a warning relating to the subject matter An example warningmight be “When deleting rows, word your WHERE clause carefully.”

Used for a series of instructions that must be followed in sequential order

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder xxiv

I

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder IĆ2

Course Objectives

At the end of this course, you should be able to

D Describe the relational database approach, concepts, terminology, and operators

D Create database structures such as tables and views using Structured QueryLanguage (SQL)

D Store, retrieve, and update data in the database

D Develop PL/SQL blocks of application code using Procedure Builder to

manipulate data

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder IĆ4

Course Outline

The course starts with an overview The first module ends on Day 3 with an optional summary covering the SQL and SQL*Plus content The second module ends on Day 5 with an optional summary of the PL/SQL section.

DAY 1

Lesson 1 Selecting Rows

Lesson 2 Limiting Selected Rows

Lesson 3 Single Row Functions

Lesson 4 Displaying Data from Multiple Tables

DAY 2

Lesson 5 Group Functions

Lesson 6 Subqueries

Lesson 7 Specifying Variables at Runtime

Lesson 8 Overview of Data Modeling and Database Design

Lesson 9 Creating Tables

Lesson 10 Oracle Data Dictionary

DAY 3

Lesson 11 Manipulating Data

Lesson 12 Altering Tables and Constraints

Lesson 13 Creating Sequences

Lesson 14 Creating Views

Lesson 15 Creating Indexes

Lesson 16 Controlling User Access

Lesson 17 Summary of SQL and SQL*Plus

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder IĆ6

Course Outline continued

DAY 4

Lesson 18 Overview of PL/SQL

Lesson 19 Basics of Procedure Builder

Lesson 20 Modularizing Programming with Subprograms

Lesson 21 Developing a Simple PL/SQL Block

Lesson 22 Interacting with Oracle

DAY 5

Lesson 23 Controlling Flow in PL/SQL Blocks

Lesson 24 Processing Queries by Using Explicit Cursors

Lesson 25 Error Handling

Lesson 26 Summary of PL/SQL

(optional)

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder IĆ8

The Relational Database Concept

The principles of the relational model were first outlined by Dr E F Codd in a June

1970 paper called “A Relational Model of Data for Large Shared Data Banks.” In thispaper, Dr Codd proposed the relational model for database systems

The more popular models used at that time were hierarchical and network, or even

simple flat file data structures Relational database management systems (RDBMS)

soon became very popular, especially for their ease of use and flexibility in structure

In addition, there were a number of innovative vendors, such as Oracle, who

supplemented the RDBMS with a suite of powerful application development and userproducts, providing a total solution

Concepts of the Relational Model

D Collections of objects or relations store the data

D A set of operators can act on the relations to produce other relations

D A relational database must possess data integrity so that its data must be accurateand consistent

An example of a relation is a table To retrieve data from the tables, use relationaloperation SQL commands

Relational Database Functions

D Manage the storage of data

D Control access to the data

D Provide a means to retrieve and modify the data

For more information, see

The Relational Model for Database Management Version 2, E F Codd, Addison

Wesley

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder IĆ10

The Relational Database Concept continuedDatabase Terminology

Concept Description

Table A table is the basic storage structure of an RDBMS, consisting

of one or more columns and zero or more rows

Row A row is a combination of column values in a table; for

example, the information about one department in the tableS_DEPT A row is sometimes called a “record”

Column A column represents one kind of data in a table; for example,

the department name in the example table S_DEPT It isdescribed with a column name and holds data of a specific typeand size

Field At the intersection of a row and a column, you find a field The

field can contain data If there is no data in the field, it is said tocontain a null value

Primary Key A primary key is the column or set of columns that uniquely

identifies each row in a table; for example a departmentnumber It must contain a value

Foreign Key A foreign key is a column or set of columns that refers to a

primary key in the same table or in another table You createthem to enforce relational database design rules

Guidelines

D No duplicate values are allowed in a primary key

D Primary keys generally cannot be changed

D Foreign keys are based on data values and are purely logical, not physical

pointers

D A foreign key value must match an existing primary key value or else be NULL

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder IĆ12

The Relational Database Concept continuedRelational Database Properties

A database is a collection of individual, named objects, such as tables You do notspecify the access route to the tables, and do not need to know how the data is

arranged physically

To access the database, you execute a Structured Query Language (SQL) command,

which is the American National Standards Institute (ANSI) standard language foroperating upon relational databases The language contains a large set of operators forpartitioning and combining relations The database can be easily modified by usingthe SQL commands The relational model allows for full data independence

Abridged List of Database Objects

Object Description

Table Basic unit of storage composed of rows and columns

View Logically represents subsets of data from one or more tables

Sequence Generates primary key values

Index Improves the performance of queries

Synonym Alternate name for an object

Program unit Procedure, function, or package of SQL and PL/SQL statements

grouped together

Table Properties

A single table is composed of rows and columns The intersection of the rows andcolumns are the field values Each row should be identified by a primary key, whichallows no duplicate rows The order of the rows is insignificant; by default, the data isordered in the order in which it was inserted Each column is uniquely named

Column order is insignificant when storing data; specify the column order when thedata is retrieved Field values cannot be broken into smaller components

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder IĆ14

The Relational Database Concept continuedProtect Data Integrity

Ensure that users perform only operations that leave the database in a correct andconsistent state with data integrity constraints All data integrity constraints should beenforced by the database server or the application software

Integrity Constraint Type Description

Entity No part of a primary key can be NULL and the

value must be unique

Referential Foreign key values must match a primary key or be

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder IĆ16