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Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ2... Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ4The SQL*Plus Environment... Introduction to Oracle

Using SQL*Plus to Create Reports and Manage PL/SQL

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Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ2

This lesson covers formatting query output to produce simple reports,

controlling the SQL*Plus environment, and manipulating PL/SQL code using SQL*Plus.

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

D Differentiate between SQL and SQL*Plus commands

D Identify SET commands used to control the SQL*Plus environment

D Customize reports using SQL*Plus formatting commands

D Create and modify anonymous blocks and program units with SQL*Plus and theonline editor

D Execute SQL*Plus commands, anonymous blocks, program units, and SQLstatements

D Compile procedures and functions

D Embed messages to assist with debugging code

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ4

The SQL*Plus Environment

SQL*Plus is an environment in which you can

D Execute SQL statements to retrieve, modify, add, and remove data from databasetables

D Format, perform calculations on, store, and print query results in the form ofreports

D Issue SQL statements to create, alter, and remove database tables

D Create anonymous blocks, subprograms, database triggers using procedurallanguage extension, PL/SQL

SQL*Plus has a variety of commands you need to use to execute subprograms, passvalues in and out of PL/SQL blocks, and debug your code

SQL*Plus commands may be divided into the following main categories

Environment Affects the general behavior of SQL statements for the

session

Format Formats query results

File manipulation Saves, loads, and runs script files

Execution Sends SQL or PL/SQL commands from SQL buffer to

Oracle7 Server

Edit Modifies SQL commands in the buffer

Interaction Allows users to create and pass variables to SQL

statements, print variable values, and print messages tothe screen

Miscellaneous Various commands to connect to the database,

manipulate the SQL*Plus environment, and displaycolumn definitions

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ6

Entering Commands in SQL*Plus

Entering Commands in SQL*Plus

Once you log in to SQL*Plus, you see the command prompt Issue all your

commands at this prompt Three types of commands can be entered at this prompt

D SQL commands to manipulate data and structures in the database

D SQL*Plus command to format query results, set the environment, edit commands,and create variables

D PL/SQL blocks to work with information in the database in a procedural method

To execute commands, type them at the command prompt SQL*Plus commands donot need to be terminated with a semicolon (;) SQL statements and PL/SQL blocks

do need to be terminated with a semicolon to send the statement to the Oracle7Server

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ8

Comparison of SQL and SQL*Plus Commands

This table compares SQL and SQL*Plus commands They are distinctly differentprograms, but are used together to perform some tasks, such as to format data in areport and to control command files

Is a language for communicating with

the Oracle Server to access data

Recognizes SQL commands, and sendsthem to the server

Is based on American National

Standards Institute (ANSI) standard

Does not have a continuation character Has a dash “-” as a continuation

character if the command is longer thanone line

Cannot be abbreviated Can be abbreviated

Uses a termination character to execute

commands required

Does not require termination characters;commands are immediately executed.Uses functions to perform some

formatting

Uses commands to format data

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ10

SQL*Plus SET Commands

Control the environment in which SQL*Plus is currently operating by using the SETcommands

Syntax

SET system_variable value

where: system_variable is a variable that controls one aspect of the

session environment

value is a value for the system variable

Default Settings Using the login.sql File

The login.sql file contains standard SET and other SQL*Plus commands that you

may require for every session The file is read and commands are implemented at log

in When you log out of your session, all customized setting are lost

Changing the Default Settings

The settings implemented by login.sql can be changed during the current session.

Changes made are only current for that session As soon as you log out, those settingsare lost

Add permanent changes to settings to the login.sql file.

For more information, see

SQL*Plus User’s Guide and Reference, Release 3.3, “Command Reference.”

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ12

SQL* Plus SET Commands

Some Useful SET Commands

SET Variable and Values Description

ARRAY[SIZE] {20|n} Sets the database data fetch size

COLSEP { |text} Sets text to be printed between columns Default

is single space

FEED[BACK] {6|n|OFF|ON} Displays the number of records returned by a

query when the query selects at least n records.

HEA[DING]{OFF|ON} Determine whether column headings are

PAGES[IZE] {24|n} Specifies the number of lines per page of output

PAU[SE] {OFF|ON|text} Allows you to control scrolling of your terminal

You must press [Return] after seeing each pause.TERM[OUT] {OFF|ON} Determines whether output is displayed to the

screen

Guidelines

D Use the SHOW command to view current values for any of these settings, forexample SHOW PAUSE To see all SET variable values, use the SHOW ALLcommand

D The value n represents a numeric value.

D Underlined values shown above indicate default values If you enter no value withthe variable, then SQL*Plus assumes the default value

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ14

Creating a Report

Script File

You can create a script file (or command file) that includes both a SQL SELECT

statement and SQL*Plus commands used to format and reset command values Scriptfiles are useful for saving both a SQL statement and any SQL*Plus settings specific

to that statement

Additionally, you can create a file to hold all your default SQL*Plus commands,which may be executed at any time to reset your settings This file can be executedfrom within your command file

SQL*Plus Format Commands

You can control the report features described above by using the following

commands:

COL[UMN] [column option] Controls column formats

TTI[TLE] [text|OFF|ON] Specifies a header to appear at the top of each

page of the report

BTI[TLE] [text|OFF|ON] Specifies a footer to appear at the bottom of

each page of the report

Guidelines

D All format commands remain in effect until the end of the SQL*Plus session, oruntil the format setting is overwritten or cleared

D Remember to reset your SQL*Plus settings to default values after every report

D There is no command for setting a SQL*Plus variable to its default value; youmust know the specific value or log out and log in again

D If you give an alias to your column, you must reference the alias name, not thecolumn name

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ16

Creating a Report continued

TTITLE and BTITLE Commands

Use the TTITLE command to format page headers and the BTITLE command forfooters Footers appear at the end of the page according to the PAGESIZE value

Syntax

The syntax for BTITLE and TTITLE is identical Only the TTITLE syntax is shown.You can use the vertical bar (|) to split the text of the title across several lines

TTI[TLE] [printspec [text|variable]][OFF|ON]

where: printspec is an option to specify the type of settings

text represents the title text Enter single quotes if

the text is more than one word

variable is a system-maintained value

Example

Set the report header to display Salary centered on one line, and Report centeredbelow it

SQL> TTITLE ’Salary|Report’

Display or Clear Settings

To show or clear the current header and footer command settings, use the followingcommands

TTITLE Displays the current setting for the header

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ18

Creating a Report continued

Creating the Script File to Run a Report

You can either enter each of the SQL*Plus commands at the SQL prompt or put allthe commands, including the SELECT statement, in a command (or script) file Atypical script consists of at least one SELECT statement and several SQL*Plus

commands

Steps to Create a Script File

1. Create the SQL SELECT statement at the SQL prompt Ensure that the datarequired for the report is accurate before you save the statement to a file andapply formatting commands Ensure that the relevant ORDER BY clause isincluded if you intend to use breaks

2. Save the SELECT statement to a script file

3. Edit the script file to enter the SQL*Plus commands

4. Add the required formatting commands before the SELECT statement Be certainnot to place SQL*Plus commands within the SELECT statement

5. Verify that the SELECT statement is followed by a run character, either a

semicolon (;) or a slash (/)

6. Add the format-clearing SQL*Plus commands after the run character As analternative, you can call a reset file which contains all the format-clearing

commands

7. Save the script file with your changes

8. In SQL*Plus, run the script file by entering START filename or @filename This

command is required to read and execute the script file

Guidelines

D You can include blank lines between SQL*Plus commands in a script

D You can abbreviate SQL*Plus commands

D Include reset commands at the end of the file in order to restore the originalSQL*Plus environment

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ20

12

Creating a Report continued

REM ** This report covers all employees who are notREM ** vice presidents or warehouse managers

SET ECHO OFF

COLUMN title HEADING ’Job|Category’ FORMAT A22

COLUMN last_name HEADING ’Employee’ FORMAT A22

COLUMN salary HEADING ’Salary’ FORMAT $99,999.99

REM ** Insert SELECT statement

SELECT title, last_name, salary

WHERE title NOT LIKE ’VP%’

ORDER BY title, last_name, salary

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ22

Declaring and Creating PL/SQL Blocks

Declaring and Creating PL/SQL Blocks

You can use two methods to process PL/SQL blocks in SQL*Plus

D Define a block in the SQL buffer, then execute the contents of the buffer

D Define a block as part of a SQL*Plus script file, then start the file

Declaring PL/SQL Blocks in the SQL Buffer

A PL/SQL block is treated as one continuous statement in the buffer, and the

semicolons (;) within the block do not close or execute the contents of the buffer.

SQL*Plus detects the start of a PL/SQL block when you enter either DECLARE orBEGIN at the prompt You can close the buffer without executing the block by

entering a period (.) at the number prompt of the buffer

To run the buffered PL/SQL block, enter the RUN command or a slash (“/”) at theprompt If the block executes successfully, without unhandled exceptions or compileerrors, you will see a message

Creating SQL*Plus Files Containing PL/SQL Blocks

You can include PL/SQL blocks in files of SQL and SQL*Plus commands Create the

file using the operating system editor SQL*Plus commands may not occur inside the

PL/SQL block itself, but you can include them elsewhere in the file

You can reference SQL*Plus substitution variables inside the block, but rememberthat they are substituted with the variable’s contents before the code is parsed orexecuted This means that if you reference a SQL*Plus substitution variable in aPL/SQL loop, then a value is substituted for the variable once, and not for eachiteration of the loop

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ24

SQL*Plus Commands

Entering Commands in SQL*Plus

SQL*Plus contains an array of commands to format reports and initiate the users’environment

SQL*Plus Command Description

ACCEPT Reads input from the user and stores the input into a

variable

VARIABLE Declares a bind, or host, variable that can be

referenced in PL/SQL with a preceding colon (:).PRINT Displays the current value of bind variables

EXECUTE Executes a single PL/SQL statement

For more information, see

SQL*Plus User’s Guide and Reference, Release 3.3.

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ26

Passing Input and Output Values

A substitution variable, or parameter, preceded by an ampersand (&) is used to represent a value to be passed into a statement A global variable preceded by a colon

(:)is used to pass information out of the PL/SQL block

2. Within the PL/SQL block, embed the SQL*Plus substitution parameter wherever

it is needed as input, referencing it with the ampersand (&) prefix

Syntax

ACCEPT variable PROMPT message

where: variable is the name of the substitution variable to store

the value

message is the message displayed

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ28

Passing Input and Output Values continued

Output Values

Output a value from the PL/SQL block into SQL*Plus by using a SQL*Plus globalvariable Follow the steps listed below

1. Outside the PL/SQL block, declare a SQL*Plus global variable with the

SQL*Plus VARIABLE command

2. Within the PL/SQL block, embed the SQL*Plus global variable wherever it isneeded as output, referencing it with the colon (:) prefix

3. Outside the PL/SQL block, print the output value on the screen with the

SQL*Plus PRINT command

Syntax

VARIABLE variable [NUMBER|CHAR|CHAR(n)|VARCHAR2(n)]

PRINT variable

where: variable is the name of the bind variable

n is the maximum length for the datatype

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ30

Debugging in SQL*Plus

When you execute your PL/SQL code, one of two types of errors might appear Onetype is a compilation error For anonymous blocks, you will see the errors appear onthe screen For stored subprograms, the compilation errors are stored in the

USER_ERRORS data dictionary table To access those errors, enter either of thefollowing commands at the prompt:

Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ32

Debugging in SQL*Plus continued

One method for debugging your PL/SQL block using SQL*Plus is to embed globalvariables at specific points with a message Each message can contain informationabout how many times a loop was executed, or which statements were executed Youcan print the results of the global variables using the SQL*Plus PRINT command

Example

Print a message indicating which DML statement was executed

VARIABLE g_debug VARCHAR2(50)

ACCEPT p_num PROMPT ’Enter a number: ’

-Introduction to Oracle: SQL and PL/SQL Using Procedure Builder CĆ34

Displaying Contents of a Subprogram

You can obtain the text of a stored procedure or a function from USER_SOURCEdata dictionary view

Example

Display contents of the procedure CHANGE_SALARY

SQL> SELECT text

TEXT

––––––––––––––––––––––––––––––––––––––––––––––––––––

(v_emp_id IN NUMBER, v_new_salary IN NUMBER) IS

BEGIN

UPDATE s_emp SET salary = v_new_salary WHERE id = v_emp_id;

COMMIT;

END change_salary;