Introduction to Oracle 11g PL/SQL · PDF fileIntroduction to Oracle 11g PL/SQL Programming...

Introduction to

Oracle 11g PL/SQL

Programming

Student Workbook

Page ii Rev 05-14-09 © 2009 ITCourseware, LLC

Introduction to Oracle 11g PL/SQL Programming


Contributing Authors: Danielle Hopkins, Julie Johnson, Rob Roselius, and Robert Seitz

Published by ITCourseware, LLC., 7245 South Havana Street, Suite 100, Centennial, CO 80112.

Copyeditor: Danielle North

Special thanks to: Many instructors whose ideas and careful review have contributed to the quality of this

workbook, including Roger Jones, Jim McNally, and Kevin Smith, and the many students who have offered

comments, suggestions, criticisms, and insights.

Copyright © 2009 by ITCourseware, LLC. All rights reserved. No part of this book may be reproduced or

utilized in any form or by any means, electronic or mechanical, including photo-copying, recording, or by an

information storage retrieval system, without permission in writing from the publisher. Inquiries should be

addressed to ITCourseware, LLC., 7245 South Havana Street, Suite 100, Centennial, Colorado, 80112.

(303) 302-5280.

All brand names, product names, trademarks, and registered trademarks are the property of their respective

owners.

© 2009 ITCourseware, LLC Rev 05-14-09 Page iii


Contents

Chapter 1 - Course Introduction ............................................................................................................. 9

Course Objectives .......................................................................................................................... 10

Course Overview ........................................................................................................................... 12

Using the Workbook ...................................................................................................................... 13

Suggested References ..................................................................................................................... 14

Sample Database ............................................................................................................................ 16

Chapter 2 - Triggers ............................................................................................................................. 21

Beyond Declarative Integrity ........................................................................................................... 22

Triggers .......................................................................................................................................... 24

Types of Triggers ............................................................................................................................ 26

Trigger Sequencing ......................................................................................................................... 28

Row-Level Triggers ........................................................................................................................ 30

Trigger Predicates ........................................................................................................................... 32

Trigger Conditions .......................................................................................................................... 34

Using SEQUENCEs ....................................................................................................................... 36

Cascading Triggers and Mutating Tables .......................................................................................... 38

Generating an Error ........................................................................................................................ 40

Maintaining Triggers ........................................................................................................................ 42

Labs ............................................................................................................................................... 44

Chapter 3 - PL/SQL Variables and Datatypes ....................................................................................... 47

Anonymous Blocks ......................................................................................................................... 48

Declaring Variables ......................................................................................................................... 50

Datatypes ....................................................................................................................................... 52

Subtypes ........................................................................................................................................ 54

Character Data ............................................................................................................................... 56

Dates and Timestamps .................................................................................................................... 58

Date Intervals ................................................................................................................................. 60

Anchored Types ............................................................................................................................. 62

Assignment and Conversions ........................................................................................................... 64

Selecting into a Variable .................................................................................................................. 66

Returning into a Variable ................................................................................................................. 68

Labs ............................................................................................................................................... 70

Page iv Rev 05-14-09 © 2009 ITCourseware, LLC


Chapter 4 - PL/SQL Syntax and Logic ................................................................................................. 73

Conditional Statements — IF/THEN............................................................................................... 74

Conditional Statements — CASE ................................................................................................... 76

Comments and Labels .................................................................................................................... 78

Loops ............................................................................................................................................ 80

WHILE and FOR Loops ................................................................................................................ 82

SQL in PL/SQL ............................................................................................................................. 84

Local Procedures and Functions ..................................................................................................... 86

Labs ............................................................................................................................................... 88

Chapter 5 - Stored Procedures and Functions ....................................................................................... 91

Stored Subprograms ....................................................................................................................... 92

Creating a Stored Procedure ........................................................................................................... 94

Procedure Calls and Parameters ..................................................................................................... 96

Parameter Modes ........................................................................................................................... 98

Named Parameter Notation .......................................................................................................... 100

Default Arguments ........................................................................................................................ 102

Creating a Stored Function ........................................................................................................... 104

Stored Functions and SQL ........................................................................................................... 106

Invoker's Rights ............................................................................................................................ 108

Labs ............................................................................................................................................. 110

Chapter 6 - Exception Handling .......................................................................................................... 113

SQLCODE and SQLERRM ........................................................................................................ 114

Exception Handlers ....................................................................................................................... 116

Nesting Blocks ............................................................................................................................. 118

Scope and Name Resolution ......................................................................................................... 120

Declaring and Raising Named Exceptions ...................................................................................... 122

User-Defined Exceptions .............................................................................................................. 124

Labs ............................................................................................................................................. 126

Chapter 7 - Records, Collections, and User-Defined Types ................................................................. 129

Record Variables .......................................................................................................................... 130

Using the %ROWTYPE Attribute ................................................................................................. 132

User-Defined Object Types .......................................................................................................... 134

VARRAY and Nested TABLE Collections .................................................................................... 136

Using Nested TABLEs ................................................................................................................. 138

Using VARRAYs .......................................................................................................................... 140

© 2009 ITCourseware, LLC Rev 05-14-09 Page v


Collections in Database Tables ...................................................................................................... 142

Associative Array Collections ........................................................................................................ 144

Collection Methods ...................................................................................................................... 146

Iterating Through Collections ......................................................................................................... 148

Labs ............................................................................................................................................. 150

Chapter 8 - Cursors ........................................................................................................................... 153

Multi-Row Queries ....................................................................................................................... 154

Declaring and Opening Cursors ..................................................................................................... 156

Fetching Rows .............................................................................................................................. 158

Closing Cursors ............................................................................................................................ 160

The Cursor FOR Loop ................................................................................................................. 162

FOR UPDATE Cursors ................................................................................................................ 164

Cursor Parameters ........................................................................................................................ 166

The Implicit (SQL) Cursor ............................................................................................................ 168

Labs ............................................................................................................................................. 170

Chapter 9 - Bulk Operations ............................................................................................................... 173

Bulk Binding ................................................................................................................................. 174

BULK COLLECT Clause ............................................................................................................ 176

FORALL Statement ..................................................................................................................... 178

FORALL Variations ...................................................................................................................... 180

Bulk Returns ................................................................................................................................. 182

Bulk Fetching with Cursors ........................................................................................................... 184

Labs ............................................................................................................................................. 186

Chapter 10 - Using Packages ............................................................................................................. 189

Packages ...................................................................................................................................... 190

Oracle-Supplied Packages ............................................................................................................ 192

The DBMS_OUTPUT Package ................................................................................................... 194

The DBMS_UTILITY Package .................................................................................................... 196

The UTL_FILE Package .............................................................................................................. 198

Creating Pipes with DBMS_PIPE ................................................................................................. 200

Writing to and Reading from a Pipe ............................................................................................... 202

The DBMS_METADATA Package .............................................................................................. 204

XML Packages ............................................................................................................................ 206

Networking Packages ................................................................................................................... 208

Other Supplied Packages .............................................................................................................. 210

Labs ............................................................................................................................................. 212

Page vi Rev 05-14-09 © 2009 ITCourseware, LLC


Chapter 11 - Creating Packages ......................................................................................................... 215

Structure of a Package .................................................................................................................. 216

The Package Interface and Implementation .................................................................................... 218

Package Variables and Package State ........................................................................................... 220

Overloading Package Functions and Procedures ........................................................................... 222

Forward Declarations ................................................................................................................... 224

Strong REF CURSOR Variables ................................................................................................... 226

Weak REF CURSOR Variables .................................................................................................... 228

Labs ............................................................................................................................................. 230

Chapter 12 - Working with LOBs ....................................................................................................... 233

Large Object Types ...................................................................................................................... 234

Oracle Directories ........................................................................................................................ 236

LOB Locators .............................................................................................................................. 238

Internal LOBs ............................................................................................................................... 240

LOB Storage and SECUREFILEs ................................................................................................ 242

External LOBs .............................................................................................................................. 244

Temporary LOBs ......................................................................................................................... 246

The DBMS_LOB Package ........................................................................................................... 248

Labs ............................................................................................................................................. 250

Chapter 13 - Maintaining PL/SQL Code ............................................................................................. 253

Privileges for Stored Programs ...................................................................................................... 254

Data Dictionary ............................................................................................................................ 256

PL/SQL Stored Program Compilation ........................................................................................... 258

Conditional Compilation ................................................................................................................ 260

Compile-Time Warnings ................................................................................................................ 262

The PL/SQL Execution Environment ............................................................................................. 264

Dependencies and Validation ......................................................................................................... 266

Maintaining Stored Programs ........................................................................................................ 268

Labs ............................................................................................................................................. 270

Appendix A - Dynamic SQL ............................................................................................................... 273

Generating SQL at Runtime ........................................................................................................... 274

Native Dynamic SQL vs. DBMS_SQL Package ........................................................................... 276

The EXECUTE IMMEDIATE Statement ...................................................................................... 278

Using Bind Variables ..................................................................................................................... 280

Multi-row Dynamic Queries .......................................................................................................... 282

© 2009 ITCourseware, LLC Rev 05-14-09 Page vii


Bulk Operations with Dynamic SQL ............................................................................................. 284

Using DBMS_SQL ...................................................................................................................... 286

DBMS_SQL Subprograms ........................................................................................................... 288

Appendix B - PL/SQL Versions, Datatypes and Language Limits ......................................................... 291

Appendix C - Oracle 11g Supplied Packages ...................................................................................... 299

Solutions ............................................................................................................................................ 311

Index .................................................................................................................................................. 343

Course IntroductionChapter 1

© 2009 ITCourseware, LLC Rev 05-14-09

Chapter 1 - Course Introduction


Rev 05-14-09 © 2009 ITCourseware, LLC

� Create triggers on database tables.

� Use PL/SQL's datatypes for database and program data.

� Use program stucture and control flow to design and write PL/SQL programs.

� Create PL/SQL stored procedures and functions.

� Write robust programs that handle runtime exceptions.

� Use PL/SQL's collection datatypes.

� Use cursors to work with database data.

� Use the packages supplied with Oracle.

� Design and write your own packages.

� Maintain and evolve your PL/SQL programs.

� Manage the security of your stored PL/SQL programs.

Course Objectives



� Audience: This course is designed for database application developers

programming in an Oracle environment.

� Prerequisites: A working knowledge of the SQL language, as well as a solid

understanding of 3GL programming is required.

� Classroom Environment:

� One workstation per student.

� Oracle Server and SQL*Plus.

Course Overview



Using the Workbook

Chapter 2 Servlet Basics

© 2002 ITCourseware, LLC Rev 2.0.0 Page 17

Add an init() method to your Today servlet that initializes a bornOn date, then print the bornOn date

along with the current date:

Today.java

...

public class Today extends GenericServlet {

private Date bornOn;

public void service(ServletRequest request,

ServletResponse response) throws ServletException, IOException

{

...

// Write the document

out.println("This servlet was born on " + bornOn.toString());

out.println("It is now " + today.toString());

}

public void init() {

bornOn = new Date();

}

}

Hands On:

The init() method is

called when the servlet is

loaded into the container.

This workbook design is based on a page-pair, consisting of a Topic page and a Support page. When you

lay the workbook open flat, the Topic page is on the left and the Support page is on the right. The Topic

page contains the points to be discussed in class. The Support page has code examples, diagrams, screen

shots and additional information. Hands On sections provide opportunities for practical application of key

concepts. Try It and Investigate sections help direct individual discovery.

In addition, there is an index for quick look-up. Printed lab solutions are in the back of the book as well as

on-line if you need a little help.

Java Servlets

Page 16 Rev 2.0.0 © 2002 ITCourseware, LLC

� The servlet container controls the life cycle of the servlet.

� When the first request is received, the container loads the servlet class

and calls the init() method.

� For every request, the container uses a separate thread to call

the service() method.

� When the servlet is unloaded, the container calls the destroy()

method.

� As with Java’s finalize() method, don’t count on this being

called.

� Override one of the init() methods for one-time initializations, instead of

using a constructor.

� The simplest form takes no parameters.

public void init() {...}

� If you need to know container-specific configuration information, use

the other version.

public void init(ServletConfig config) {...

� Whenever you use the ServletConfig approach, always call the

superclass method, which performs additional initializations.

super.init(config);

The Servlet Life Cycle

The Topic page provides

the main topics for

classroom discussion.

The Support page has

additional information,

examples and suggestions.

Code examples are in afixed font and shaded. The

on-line file name is listed

above the shaded area.

Screen shots show

examples of what you

should see in class.

Topics are organized into

first (�), second (�) and

third (�) level points.

Pages are numbered

sequentially throughout

the book, making lookup

easy.

Callout boxes point out

important parts of the

example code.



Allen, Christopher. 2004. Oracle Database 10g PL/SQL 101. McGraw-Hill Osborne, Emeryville, CA.

ISBN 0072255404

Boardman, Susan, Melanie Caffrey, Solomon Morse, and Benjamin Rosenzweig. 2002. Oracle Web

Application Programming for PL/SQL Developers. Prentice Hall PTR, Upper Saddle River,

NJ. ISBN 0130477311

Date, C.J and Hugh Darwen. 1996. A Guide to SQL Standard. Addison-Wesley, Boston, MA.

ISBN 0201964260

Date, C.J. 2003. An Introduction to Database Systems. Addison-Wesley, Boston, MA.

ISBN 0321197844

Feuerstein, Steven, Charles Dye, and John Beresniewicz. 1998. Oracle Built-in Packages. O'Reilly and

Associates, Sebastopol, CA. ISBN 1565923758

Feuerstein, Steven. 2007. Oracle PL/SQL Best Practices, Second Edition. O'Reilly and Associates,

Sebastopol, CA. ISBN 0596514107

Feuerstein, Steven. 2000. Oracle PL/SQL Developer's Workbook. O'Reilly and Associates, Sebastopol,

CA. ISBN 1565926749

Feuerstein, Steven and Bill Pribyl. 2005. Oracle PL/SQL Programming, Fourth Edition. O'Reilly and

Associates, Sebastopol, CA. ISBN 0596009771

Loney, Kevin. 2004. Oracle Database 10g: The Complete Reference. McGraw-Hill Osborne,

Emeryville, CA. ISBN 0072253517

McDonald, Connor, Chaim Katz, Christopher Beck, Joel R. Kallman, and David C. Knox. 2004.

Mastering Oracle PL/SQL: Practical Solutions. Apress, Berkeley, CA.

ISBN 1590592174

McLaughlin, Michael. 2008. Oracle Database 11g PL/SQL Programming. McGraw-Hill Osborne,

Emeryville, CA. ISBN 0071494456

Pribyl, Bill. 2001. Learning Oracle PL/SQL. O'Reilly and Associates, Sebastopol, CA.

ISBN 0596001800

Price, Jason. 2004. Oracle Database 10g SQL. McGraw-Hill Osborne, Emeryville, CA.

ISBN 0072229810

Suggested References



Rosenzweig, Benjamin and Elena Silvestrova Rakhimov. 2008. Oracle PL/SQL by Example. Prentice Hall

PTR, Upper Saddle River, NJ. ISBN 0137144229

Urman, Scott and Michael McLaughlin. 2004. Oracle Database 10g PL/SQL Programming. McGraw-

Hill Osborne, Emeryville, CA. ISBN 0072230665

asktom.oracle.com

www.oracle.com/technology/tech/pl_sql

tahiti.oracle.com



Sample Database

Our company is a hardware/software retailer with stores in several cities.

We keep track of each person's name, address, and phone. In addition, if a person is

an employee, we must record in which store he or she works, the supervisor's ID, the

employees's title, pay amount, and compensation type ("Hourly," "Salaried," etc.)

Sometimes a customer will fill out an order, which requires an invoice number. Each

invoice lists the store and the customer's ID. We record the quantity of each item on

the invoice and any discount for that item. We also keep track of how much the

customer has paid on the order.

When a credit account is used for an order, the balance for the account must be

updated to reflect the total amount of the invoice (including tax). The salesperson

verifies (with a phone call) that the person is a valid user of the account.

Each product we sell has a product ID and description. In addition, we keep track of

the vendor we purchase that product from, the ID for that product, and the category

("Software," "Peripheral," or "Service"). We also store the address, phone, and sales

rep ID for each individual vendor.

We keep track of how many items are on hand at each store and how many each store

has on order. When an item is sold, the inventory is updated.

We maintain the address, phone number, and manager ID for each store. Each store

has a unique store number. We record the sales tax rate for that store.

When a store runs low on a product, we create a purchase order. Each purchase

order in our company has a unique PO number. A PO is sent to a single vendor, from

which we might be ordering several items, each at a specific unit cost. The inventory

reflects the sale or order of any item in a store.



ACCOUNT_TYPE_CODE = ACCOUNT_TYPE_CODE

ID = CUSTOMER_ID

ID = SUPERVISOR_ID

PAY_TYPE_CODE = PAY_TYPE_CODE

ID = ID

PRODUCT_ID = PRODUCT_ID

STORE_NUM BER = STORE_NUM BER

ACCOUNT_NUMBER = ACCOUNT_NUM BER

ID = CUSTOM ER_ID


INVOICE_NUMBER = INVOICE_NUMBER



VENDOR_ID = VENDOR_ID

PO_NUM BER = PO_NUMBERPRODUCT_ID = PRODUCT_ID

PRODUCT_CATEGORY_CODE = PRODUCT_CATEGORY_CODE


ID = VENDOR_REP_ID

ACCOUNT

ACCOUNT_NUMBER

ACCOUNT_NAME

ACCOUNT_TYPE_CODE

CUSTOMER_ID

CREDIT_LIM IT

BALANCE

STREET

CITY

STATE

NUMBER

VARCHAR2(25)

CHAR(1)

NUMBER

NUMBER(9,2)

NUMBER(9,2)

VARCHAR2(45)

VARCHAR2(25)

CHAR(2)

ACCOUNT_TYPE

ACCOUNT_TYPE_CODE

ACCOUNT_TYPE_NAME

INITIAL_DISCOUNT

CHAR(1)

VARCHAR2(15)

NUMBER(3,3)

EMPLOYEE

ID

STORE_NUMBER

PAY_TYPE_CODE

PAY_AMOUNT

TITLE

SUPERVISOR_ID

NUMBER

NUMBER

CHAR(1)

NUMBER(9,2)

VARCHAR2(15)

NUMBER

INVENTORY

PRODUCT_ID

STORE_NUMBER

QUANTITY_ON_HAND

QUANTITY_ON_ORDER

VARCHAR2(11)

NUMBER

NUMBER

NUMBER

ORDER_HEADER

INVOICE_NUMBER

STORE_NUMBER

CUSTOMER_ID

ACCOUNT_NUMBER

ORDER_DATE

EST_DELIVERY_DATE

DELIVERY_DATE

AMOUNT_DUE

NUMBER

NUMBER

NUMBER

NUMBER

DATE

DATE

DATE

NUMBER(9,2)

ORDER_ITEM

INVOICE_NUMBER

PRODUCT_ID

QUANTITY

DISCOUNT

NUMBER

VARCHAR2(11)

NUMBER

NUMBER(3,3)

PAY_TYPE

PAY_TYPE_CODE

PAY_TYPE_NAME

M INIMUM_WAGE

CHAR(1)

VARCHAR2(15)

NUMBER(9,2)

PERSON

ID

LASTNAME

FIRSTNAME

M I

STREET

CITY

STATE

ZIP

AREA_CODE

PHONE_NUMBER

NUMBER

VARCHAR2(25)

VARCHAR2(15)

CHAR(1)

VARCHAR2(45)

VARCHAR2(25)

CHAR(2)

CHAR(9)

CHAR(3)

CHAR(7)

PO_HEADER

PO_NUMBER

VENDOR_ID

STORE_NUMBER

ORDER_DATE

TAX_RATE

NUMBER

VARCHAR2(4)

NUMBER

DATE

NUMBER(5,5)

PO_ITEM

PO_NUMBER

VENDOR_PART_NUMBER

QUANTITY

UNIT_COST

PRODUCT_ID

NUMBER

VARCHAR2(20)

NUMBER

NUMBER(7,2)

VARCHAR2(11)

PRODUCT

PRODUCT_ID

DESCRIPTION

VENDOR_ID

VENDOR_PART_NUMBER

PRICE

REORDER_THRESHOLD

PRODUCT_CATEGORY_CODE

WARRANTY_TEXT

PRODUCT_IMAGE

VARCHAR2(11)

VARCHAR2(75)

VARCHAR2(4)

VARCHAR2(20)

NUMBER(7,2)

NUMBER

CHAR(1)

CLOB

BLOB

PRODUCT_CATEGORY


PRODUCT_CATEGORY_NAME

CHAR(1)

VARCHAR2(15)

STORE

STORE_NUMBER

MANAGER_ID

STREET

CITY

STATE

ZIP

AREA_CODE

PHONE_NUMBER

SALES_TAX_RATE

NUMBER

NUMBER

VARCHAR2(45)

VARCHAR2(25)

CHAR(2)

CHAR(9)

CHAR(3)

CHAR(7)

NUMBER(5,5)

VENDOR

VENDOR_ID

NAME

VENDOR_REP_ID

STREET

CITY

STATE

ZIP

COUNTRY

AREA_CODE

PHONE_NUMBER

VARCHAR2(4)

VARCHAR2(40)

NUMBER

VARCHAR2(45)

VARCHAR2(25)

CHAR(2)

CHAR(9)

VARCHAR2(15)

CHAR(3)

CHAR(7)

© 2009 ITCourseware, LLC

ACCOUNT_TYPE_CODE = ACCOUNT_TYPE_CODE

ID = CUSTOMER_ID

ID = SUPERVISOR_ID

PAY_TYPE_CODE = PAY_TYPE_CODE

ID = ID


STORE_NUMBER = STORE_NUMBER

ACCOUNT_NUMBER = ACCOUNT_NUMBER

ID = CUSTOMER_ID


INVOICE_NUMBER = INVOICE_NUMBER




PO_NUMBER = PO_NUMBERPRODUCT_ID = PRODUCT_ID

PRODUCT_CATEGORY_CODE = PRODUCT_CATEGORY_CODE


ID = VENDOR_REP_ID

ACCOUNT

ACCOUNT_NUMBER

ACCOUNT_NAME

ACCOUNT_TYPE_CODE

CUSTOMER_ID

CREDIT_LIM IT

BALANCE

STREET

CITY

STATE

NUMBER

VARCHAR2(25)

CHAR(1)

NUMBER

NUMBER(9 ,2)

NUMBER(9 ,2 )

VARCHAR2(45)

VARCHAR2(25)

CHAR(2)

ACCOUNT_TYPE

ACCOUNT_TYPE_CODE

ACCOUNT_TYPE_NAME

INITIAL_DISCOUNT

CHAR(1)

VARCHAR2(15)

NUMBER(3 ,3 )

EMPLOYEE

ID

STORE_NUMBER

PAY_TYPE_CODE

PAY_AMOUNT

TITLE

SUPERVISOR_ID

NUMBER

NUMBER

CHAR(1)

NUMBER(9,2)

VARCHAR2(15)

NUMBER

INVENTORY

PRODUCT_ID

STORE_NUMBER

QUANTITY_ON_HAND

QUANTITY_ON_ORDER

VARCHAR2(11)

NUMBER

NUMBER

NUMBER

ORDER_HEADER

INVOICE_NUMBER

STORE_NUMBER

CUSTOMER_ID

ACCOUNT_NUMBER

ORDER_DATE

EST_DELIVERY_DATE

DELIVERY_DATE

AMOUNT_DUE

NUMBER

NUMBER

NUMBER

NUMBER

DATE

DATE

DATE

NUMBER(9,2)

ORDER_ITEM

INVOICE_NUMBER

PRODUCT_ID

QUANTITY

DISCOUNT

NUMBER

VARCHAR2(11)

NUMBER

NUMBER(3,3)

PAY_TYPE

PAY_TYPE_CODE

PAY_TYPE_NAME

MINIMUM_WAGE

CHAR(1)

VARCHAR2(15)

NUMBER(9,2)

PERSON

ID

LASTNAME

FIRSTNAME

MI

STREET

CITY

STATE

ZIP

AREA_CODE

PHONE_NUMBER

NUMBER

VARCHAR2(25)

VARCHAR2(15)

CHAR(1)

VARCHAR2(45)

VARCHAR2(25)

CHAR(2)

CHAR(9)

CHAR(3)

CHAR(7)

PO_HEADER

PO_NUMBER

VENDOR_ID

STORE_NUMBER

ORDER_DATE

TAX_RATE

NUMBER

VARCHAR2(4)

NUMBER

DATE

NUMBER(5,5)

PO_ITEM

PO_NUMBER

VENDOR_PART_NUMBER

QUANTITY

UNIT_COST

PRODUCT_ID

NUMBER

VARCHAR2(20)

NUMBER

NUMBER(7 ,2)

VARCHAR2(11)

PRODUCT

PRODUCT_ID

DESCRIPTION

VENDOR_ID

VENDOR_PART_NUMBER

PRICE

REORDER_THRESHOLD


WARRANTY_TEXT

PRODUCT_IMAGE

VARCHAR2(11)

VARCHAR2(75)

VARCHAR2(4)

VARCHAR2(20)

NUMBER(7 ,2 )

NUMBER

CHAR(1)

CLOB

BLOB

PRODUCT_CATEGORY


PRODUCT_CATEGORY_NAME

CHAR(1)

VARCHAR2(15)

STORE

STORE_NUMBER

MANAGER_ID

STREET

CITY

STATE

ZIP

AREA_CODE

PHONE_NUMBER

SALES_TAX_RATE

NUMBER

NUMBER

VARCHAR2(45)

VARCHAR2(25)

CHAR(2)

CHAR(9)

CHAR(3)

CHAR(7)

NUMBER(5,5)

VENDOR

VENDOR_ID

NAME

VENDOR_REP_ID

STREET

CITY

STATE

ZIP

COUNTRY

AREA_CODE

PHONE_NUMBER

VARCHAR2(4)

VARCHAR2(40)

NUMBER

VARCHAR2(45)

VARCHAR2(25)

CHAR(2)

CHAR(9)

VARCHAR2(15)

CHAR(3)

CHAR(7)

Stored Procedures and FunctionsChapter 5

© 2009 ITCourseware, LLC Rev 05-14-09 Page 91

Chapter 5 - Stored Procedures and Functions

Objectives

� Write and run stored procedures.

� Define stored procedure parameters,

with and without default values.

� Choose appropriate parameter

modes.

� Use named notation to invoke

subprograms with parameters in

arbitrary order.

� Provide default arguments for

parameters.

� Write and run stored functions.

� Run programs with invoker's rights

instead of definer's rights.


Page 92 Rev 05-14-09 © 2009 ITCourseware, LLC

� A PL/SQL program with no specification is called an anonymous block.

DECLARE

declarations

BEGIN

statements

END;

� Kept in script files, anonymous blocks are often used by DBAs and

developers for routine tasks.

� A trigger is a stored PL/SQL subprogram with a name:

CREATE TRIGGER triggername

{BEFORE|AFTER} {INSERT|UPDATE|DELETE}

ON tablename

DECLARE

declarations

BEGIN

statements

END;

� Compiled and stored in the system catalog, triggers are invoked (fired)

automatically, any time the specified DML statement happens.

� Stored functions and stored procedures are also named PL/SQL subprograms.

� Stored in the system catalog, stored functions and procedures are invoked

by name, from other subprograms or applications.

Stored Subprograms



anonymous.sqlDECLARE

lname VARCHAR2(25) := 'Grumby';

fname VARCHAR2(25) := 'Jonus';

BEGIN

INSERT INTO person(id, firstname, lastname)

VALUES (person_id_seq.NEXTVAL, fname, lname);

END;

/

Trigger:

person_id_check.sqlCREATE OR REPLACE TRIGGER person_id_check

BEFORE INSERT ON person

FOR EACH ROW

WHEN (new.id IS NULL)

BEGIN

:new.id := person_id_seq.NEXTVAL;

END;

/

DML which fires this trigger:

INSERT INTO person (firstname, lastname)

VALUES ('Fred', 'Dobbs')



� A stored procedure's specification includes the procedure's name, as well as the

names and datatypes of any parameters:

CREATE [OR REPLACE] PROCEDURE procedurename

[(parm1 datatype1[, parm2 datatype2...])]

AS

[declarations]

BEGIN

statements

END;

� Parameters use unconstrained datatypes.

� Specify only the datatypes of parameters, such as NUMBER or

VARCHAR2; do not include the size.

� To create a procedure you must have the CREATE PROCEDURE privilege.

� Once created, a stored procedure is a permanent part of your schema.

Creating a Stored Procedure



The declaration section of a stored procedure begins with the word AS (or the word IS, whichever

you prefer):

create_account_type1.sqlCREATE OR REPLACE PROCEDURE create_account_type

(code CHAR, name VARCHAR2, disc NUMBER)

AS

BEGIN

INSERT INTO account_type

VALUES (code, name, disc);

END;

/

You can use anchored types in defining the formal parameters:

create_account_type2.sqlCREATE OR REPLACE PROCEDURE create_account_type

(code account_type.account_type_code%TYPE,

name account_type.account_type_name%TYPE,

disc account_type.initial_discount%TYPE)

AS

BEGIN

INSERT INTO account_type

VALUES (code, name, disc);

END;

/

Note:The SQL*Plus SHOW ERRORS command formats and prints errors from the most recent compilation of

a database object.

SQL> SHOW ERRORS

...

SQL> SHOW ERRORS PROCEDURE procedurename

...

SQL> SHOW ERRORS FUNCTION functionname

...



Procedure Calls and Parameters

� A stored procedure can be called in any PL/SQL block invoked by a user with

EXECUTE privilege on the procedure.

BEGIN

create_account_type('F', 'Family', .10);

END;

� You can also execute a single PL/SQL statement or stored procedure in

SQL*Plus using the EXECUTE, or EXEC, command.

EXEC create_account_type('F', 'Family', .10);

� SQL*Plus just rewrites the EXECUTE statement as a

BEGIN...END; block.

� Parameters provide a mechanism for passing information in and out of

subprograms.

� They allow subprograms to be flexible.

� Inside of the procedure code, the parameters are used like local variables.

� When calling a stored procedure, parentheses are only used if there are values

being passed.

calculate_end_of_month;

� Arguments passed can be literal values or variables.

create_account_type(new_code, new_type, .10);



change_price.sqlCREATE OR REPLACE PROCEDURE change_price

(p_id product.product_id%TYPE, new_price product.price%TYPE)

AS

old_price product.price%TYPE;

BEGIN

SELECT price INTO old_price

FROM product

WHERE product_id = p_id;

IF ABS(new_price - old_price) < (old_price * 0.2) THEN

UPDATE product

SET price = new_price

WHERE product_id = p_id;

END IF;

END;

/

change_price_test.sqlDECLARE

prod product.product_id%TYPE;

price product.price%TYPE;

BEGIN

prod := 'XRX0000003';

price := 56.00;

change_price(prod, price); -- Pass variables

change_price('WDC0000020', 35.50); -- Pass literals

END;

/



� A parameter's mode determines how a subprogram can use it.

... procedurename(paramname MODE datatype,...)

� IN mode (the default mode) allows a value to be passed in to the procedure.

� An IN mode parameter's initial value is taken from the value passed.

� The caller can pass a variable, literal, or expression.

� IN mode parameters are read-only (the subprogram can't assign to the

parameter variable); they act as constants.

� Since IN mode parameters are read-only they are passed by reference.

� OUT mode allows the procedure to place a value into the variable passed.

� OUT mode parameters have an initial value of NULL.

� The caller must pass a variable, not a literal or an expression.

� IN OUT mode allows an incoming value to be modified and passed back from

the procedure.

� An IN OUT mode parameter's initial value is the value of the variable

passed.

� The caller must pass a variable, not a literal or an expression.

� OUT and IN OUT parameters are passed by value, so the value of the argument

won't be changed in case of an exception.

� You cannot specify default values for OUT and IN OUT parameters.

Parameter Modes



Within a subprogram, an OUT mode parameter acts like an uninitialized variable:

get_manager_name.sqlCREATE OR REPLACE PROCEDURE get_manager_name

(store_no store.store_number%TYPE, manager_name OUT VARCHAR2)

AS

BEGIN

SELECT firstname || ' ' || lastname

INTO manager_name

FROM person INNER JOIN store ON (id = manager_id)

WHERE store_number = store_no;

END;

/

The actual parameters you pass to a procedure must be variables for OUT or IN OUT parameters:

manager_name_test.sqlVAR mname VARCHAR2(40)

DECLARE

name VARCHAR2(40);

BEGIN

get_manager_name(5,name);

:mname := name;

END;

/

PROMPT The manager for store number 5 is

PRINT mname

Note:According to the PL/SQL documentation, OUT mode parameters cannot be assigned from or used in

expressions; that is, they are "write-only." However, this restriction was relaxed in versions of Oracle above

7.3.4. You can now assign from OUT mode parameters and use them in expressions. Within the subprogram,

their initial value is NULL (regardless of the value of the variable passed as an actual parameter).



Named Parameter Notation

� Up to now, we have been using positional notation for the actual parameters when

calling procedures and functions.

orders.count_po( '01-APR-96', '30-JUN-96', :second_quarter );

� The order of the actual parameters matches the order of the formal

parameters given in the specification.

� Using named notation, you may specify the actual parameters in any order.

count_po1( total => :first_quarter,

start_dt => '01-JAN-96', end_dt => '31-MAR-96');

� You may also mix both positional and named notation.

count_po1( '01-OCT-96', NULL, total => :last_quarter);

� Once you use named notation for one parameter, all subsequent parameters

in the list require named notation.

� You must use named notation if an overloaded function or procedure's signature is

not unique.

a := hr2.get_emps(state=>'CO');

a := hr2.get_emps(city=>'Denver');

� Subprograms can be overloaded if they are local to a block or declared

within a package.



orders1.sqlCREATE OR REPLACE PROCEDURE count_po1(

start_dt DATE, end_dt DATE, total OUT NUMBER)

AS

BEGIN

IF end_dt IS NULL THEN

SELECT count(po_number)

INTO total

FROM po_header

WHERE order_date >= start_dt;

ELSE


INTO total

FROM po_header

WHERE order_date BETWEEN start_dt AND end_dt;

END IF;

END count_po1;

/

call_orders1.sqlVAR first_quarter NUMBER

VAR second_quarter NUMBER

VAR last_quarter NUMBER

VAR yearly_total NUMBER

BEGIN

count_po1( total => :first_quarter,

start_dt => '01-JAN-96', end_dt => '31-MAR-96');

count_po1( '01-APR-96', '30-JUN-96', :second_quarter );

count_po1( '01-OCT-96', NULL, total => :last_quarter);

count_po1( '01-JAN-96', NULL, total => :yearly_total );

END;

/

PRINT first_quarter

PRINT second_quarter

PRINT last_quarter

PRINT yearly_total



Default Arguments

� You can specify a default value for IN mode parameters.

start_date DATE DEFAULT '01-JAN-96'

� If no actual parameter is passed, the formal parameter is initialized with the

default value.

� You can use the assignment operator instead of the word DEFAULT.

start_date DATE := '01-JAN-96'

� With default arguments, you can create stored procedures and functions that are

very flexible, allowing the caller to pass as many values as they need.

� In creating the parameter list, you should put the required arguments first, and

the ones that are most likely to have their defaults taken last.

CREATE OR REPLACE PROCEDURE count_po2(

total OUT NUMBER,

start_dt DATE DEFAULT '01-JAN-96',

end_dt DATE DEFAULT NULL)

� With this organization, it allows the caller to avoid the need for named

notation, as they can simply provide values from left to right.



orders2.sqlCREATE OR REPLACE PROCEDURE count_po2(

total OUT NUMBER,

start_dt DATE DEFAULT '01-JAN-96',

end_dt DATE DEFAULT NULL)

AS

BEGIN

IF end_dt IS NULL THEN


INTO total

FROM po_header

WHERE order_date >= start_dt;

ELSE


INTO total

FROM po_header

WHERE order_date BETWEEN start_dt AND end_dt;

END IF;

END count_po2;

/

call_orders2.sql

VAR first_quarter NUMBER

VAR second_quarter NUMBER

VAR last_quarter NUMBER

VAR yearly_total NUMBER

BEGIN

count_po2( :first_quarter, end_dt => '31-MAR-96');

count_po2( :second_quarter, '01-APR-96', '30-JUN-96' );

count_po2( :last_quarter, '01-OCT-96');

count_po2( :yearly_total );

END;

/

PRINT first_quarter

PRINT second_quarter

PRINT last_quarter

PRINT yearly_total



� A function is like a procedure, but it returns a value:

CREATE [OR REPLACE] FUNCTION functionname

[(parm1 datatype1[, parm2 datatype2...])]

RETURN datatype

AS

[declarations]

BEGIN

statements

RETURN value;

END;

� If you're declaring a function, you must specify its return type, and it must

actually return a value of that type.

� The function body must contain a RETURN statement, which returns a value of

the specified type.

SELECT sales_tax_rate INTO rate FROM store

WHERE store_number = s;

RETURN rate;

� You can't create two stored functions, or a stored function and a stored

procedure, with the same name.

� Use CREATE OR REPLACE to redefine an existing function or

procedure.

CREATE OR REPLACE FUNCTION get_tax_rate(s NUMBER)

RETURN NUMBER AS ...

� As a general rule, functions should use only IN mode parameters.

� Use a function to take zero or more parameters, and compute and return

exactly one data item.

Creating a Stored Function



get_tax_rate.sqlCREATE OR REPLACE FUNCTION get_tax_rate (snum NUMBER)

RETURN NUMBER

AS

rate store.sales_tax_rate%TYPE;

BEGIN

SELECT sales_tax_rate INTO rate FROM store

WHERE store_number = snum;

RETURN rate;

END;

/

The following function will return the total for sales on a particular day. If a date is not provided, then the

current system date is used.

order_daily_total.sqlCREATE OR REPLACE FUNCTION order_daily_total

(in_date DATE DEFAULT SYSDATE)

RETURN NUMBER

AS

daily_total NUMBER;

BEGIN

SELECT sum(price * quantity) INTO daily_total

FROM product INNER JOIN order_item USING (product_id)

INNER JOIN order_header USING (invoice_number)

WHERE order_date = in_date;

RETURN daily_total;

END;

/



� You can call a stored function, or a package function, in SQL statements (just

like a built-in function), if the function meets certain requirements, including:

� It must have only IN mode parameters.

� Parameters and the return value must have SQL datatypes;

BINARY_INTEGER or BOOLEAN, for example, are not allowed, nor

are record or collection types.

� In addition, a stored or package function called in SQL statements can have no

adverse side effects.

� It cannot update database data.

� If called anywhere other than a SELECT list, VALUES clause, or SET

clause, then it cannot change package variable values.

� It cannot call any functions or procedures that break these rules.

� The level of compliance with these and other restrictions is termed purity.

� The PL/SQL compiler determines the purity level of stand-alone stored

functions when they are compiled.

� Purity levels had to be asserted by the programmer, using PRAGMA

RESTRICT_REFERENCES, prior to Oracle 8i.

Stored Functions and SQL



get_tax_rate2.sqlSELECT sum(quantity * price * (1 + get_tax_rate(store_number)))

FROM order_header JOIN order_item USING (invoice_number)

JOIN product USING (product_id)

WHERE order_date = '01-MAR-96'

/

Oracle Database 10g (and earlier versions) allow only positional parameter notation when you call a stored

function from a SQL statement:

store_tax_rates1.sql

SELECT store_number, get_tax_rate(store_number)

FROM store

/

Starting with 11g, you can use named parameter notation when calling a stored function in SQL:

store_tax_rates2.sql

SELECT store_number, get_tax_rate(snum => store_number)

FROM store

/



Invoker's Rights

� By default, stored PL/SQL program units execute with the privileges and schema

context of the creator of the unit, rather than the user who is executing the code.

� Use the AUTHID clause to override this default behavior.

AUTHID CURRENT_USER

� This signals that the program will execute using the rights of the user

currently executing the stored program.

� When the AUTHID clause is used for a package, it is defined in the package

specification and applies to all routines in the package.

� Priviliges are checked when executing a stored subprogram.

� Invoker's rights will require that the invoker (current user) has all of the

necessary privileges for the tables and other subprograms being

manipulated.

� Using the invoker's schema context means that object resolution will be based

on the invoker's schema, not the schema of the user that defined the

subprogram.

� Each user may have different synonyms, tables, and views defined.

� Make sure that tables and views are fully qualified with their schema

name to avoid confusion.

� You can explicitly specify the default behavior of definer's rights with the

AUTHID clause.

AUTHID DEFINER



Consider a procedure which updates an unqualified reference to emp.

With invoker's rights, a user would need to have the DELETE privilege on the emp table. And, the

resolution of emp would depend on the current user's schema definition.

delete_emp1.sqlCREATE OR REPLACE PROCEDURE delete_emp1 (in_empid NUMBER)

AUTHID CURRENT_USER IS

BEGIN

DELETE FROM emp

WHERE id = in_empid;

END;

/

The same procedure using definer's rights would not require the invoker to have the DELETE privilege on

emp, only the EXECUTE privilege on the procedure. Additionally, the resolution of emp would be based

on the schema of the procedure's creator, not the user running it.

delete_emp2.sqlCREATE OR REPLACE PROCEDURE delete_emp2 (in_empid NUMBER)

AUTHID DEFINER IS

BEGIN

DELETE FROM emp

WHERE id = in_empid;

END;

/

Try It:Log into the database as s1, and create a synonym of emp:

CREATE SYNONYM emp FOR employees;

Then, create each of the procedures above:

@delete_emp1

@delete_emp2

Grant EXECUTE privilege on these procedures to the s2 user:

GRANT EXECUTE ON delete_emp1 TO s2;

GRANT EXECUTE ON delete_emp2 TO s2;

Now log in as the s2 user and try executing each procedure:

EXEC s1.delete_emp1(8044); -- this call fails

EXEC s1.delete_emp2(8044); -- this call succeeds



� Create a stored procedure named raise_pay that will increase an employee's pay amount. The

parameters should be the employee's id number and the percent increase to his salary. Use 3% as

the default percent increase.

(Solution: raise_pay.sql)

� Create a stored function called emp_count that returns a number. Allow the function to be called

with a state code as a parameter. If a state is provided, then return the number of employees in that

state. If no state is provided, then return the total number of employees.

(Solutions: emp_count.sql, emp_count_test.sql)

� Create a stored function called get_store that takes a city and state as its parameters and

returns a store number. Create an anonymous block of code to call this function on the Las Vegas,

NV store, putting the result into a bind variable.

(Solution: getstore.sql)

Labs

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