ISYS 365 – SQL*Plus Environment

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Agenda What is SQL*Plus?

Command Line Editor

Useful SQL*Plus Commands

Useful System Tables

What is PL/SQL?

PL/SQL Constructs

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What is SQL*Plus?

Oracle’s development environment

Used to write, test and debug SQL and PL/SQL code

Hasn’t changed much in 20 years

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Command Line Editor list or list # change

Example: /Featuer/Feature (can use any delimiter) del

del (current line only) del 3 7 (range of lines) del 2 LAST (deletes from line 2 to the end of the

buffer) Do NOT use the word “delete”

clear buffer: clears out the SQL statement

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Command Line Editor append

Places text at the end of the current line without any spaces between the existing text & the appended text

input

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Useful SQL*Plus Commands set headsep: identifies the character that tells SQL*Plus

when to split a title or column onto 2 or more lines Default character: |

SQL> SELECT LNAME "Last_Name|Of|Employee"

will display Last_Name Of Employee ---------------

Set headsep ! ttitle: sets the title at the top of each page

ttitle ‘Sales by Product During 1901!Second Six Months’ If title should display an apostrophe, then use two single

quotes btitle: sets the title at the bottom of each page

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Useful SQL*Plus Commands column: tells SQL*Plus how to handle columns

Can be used to re-label column headings column Item heading ‘What Was!Sold’

Can be used to specify column format column Item format a18 column Rate format 90.99

zero tells SQL*Plus to pad the number with a zero (if necessary)

999,999,999 99.90 Can be used to truncate data in column

column Item truncated (OR column Item trunc) Can be used to wrap info

column Item word_wrapped

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Useful SQL*Plus Commands column: tells SQL*Plus how to handle

columns Can be used to specify column format

Alphanumeric: column Item format a18 Numeric: column Rate format 90.99

Use nines and zeros to specify the numeric pattern Examples: (a) 999,999,999 (b) 99.90

COLUMN Salary FORMAT $999,999.99 See “numeric formatting” in Oracle Complete

Reference

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Useful SQL*Plus Commands break on: tells SQL*Plus where to break for subtotals

and totals break on Item skip 2

will not repeat the value in the Item column Create one line for each unique Item value and skip 2 lines

break on Item duplicate skip 2 will repeat the value in the Item column

must be coordinated with the order by clause break on report

tells SQL*Plus to provide a grand total for the report Example: break on Item skip 2 on report

break on report on Item skip 2

compute sum: tells SQL*Plus to calculate subtotals works in conjunction with the break on command

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Useful SQL*Plus Commands Basic rules for computing subtotals & totals:

Every break on must have a related order by Consecutive break on commands will override the

previous break on command To create both subtotals & totals, combine the

break on instructions as follows break on X skip # on report OR break on report on X skip # where X = column name & # = lines to skip between

sections Every compute sum must have a related break on Clear breaks and computes before setting up new

ones

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Useful SQL*Plus Commands set linesize

sets the maximum number of characters allowed on any line; usually 70 or 80

set pagesize sets the maximum number of lines per

page; usually 66 lines set newpage

sets the number of blank lines between pages

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Useful SQL*Plus Commands spool & spool off

Example: spool test.sql run (/) start (@) save

saves the SQL statements, but not the SQL*Plus commands

Example: save example.sql (or save example.sql replace)

store saves the current SQL*Plus environment Example: store set my_settings.sql create

(or …replace or …append)

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Useful SQL*Plus Commands To check the current settings

column (or column column_name) ttitle btitle break compute show headsep show linesize show pagesize show newpage

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Useful SQL*Plus Commands To clear the current settings

ttitle off btitle off clear columns clear breaks clear computes

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Useful System Tables User_Constraints

Useful fields: constraint_name, table_name, constraint_type

constraint_type: C, P, R & U User_Cons_Columns

Useful fields: constraint_name, column_name, position SELECT column_name

FROM user_cons_columns WHERE constraint_name=‘SYS_C0008791’;

Retrieving constraints defined by the userWHERE CONSTRAINT_NAME NOT LIKE '%SYS%';

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Useful System Tables

user_sequences Contains sequences owned by the

current user user_errors

Contains compilation errors for the current user

Use the ‘show errors’ SQL*Plus command to view the errors in the user_errors table

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What Is PL/SQL? PL/SQL stands for Procedural Language

operating on or using SQL Combines the flexibility of SQL (4GL) with the

power and configurability of the procedural constructs of a 3GL

Extends SQL by adding 3GL constructs such as:

Variables and types (predefined and user defined) Control Structures (IF-THEN-ELSE, Loops) Procedures and functions Object types and methods

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PL/SQL Constructs PL/SQL based on Ada language

constructs Block Structure Error Handling Variables and Types Conditionals Looping Constructs Cursors

Introduction to PL / SQL

Chapter 1

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What Is PL / SQL PL/SQL stands for Procedural Language

operating on or using SQL Combines power and flexibility of SQL

(4GL) with procedural constructs of a 3GL

Extends SQL by adding Variables and types Control Structures Procedures and functions Object types and methods

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File 3gl_4gl.sqlDemonstrates both SQL and PL/SQL

commands DECLARE

v_NewMajor VARCHAR2(10) := 'History';

v_FirstName VARCHAR2(10) := 'Scott';

v_LastName VARCHAR2(10) := 'Urman';

BEGIN

UPDATE students

SET major = v_NewMajor

WHERE first_name = v_FirstName

AND last_name = v_LastName;

IF SQL%NOTFOUND THEN

INSERT INTO students (ID, first_name, last_name, major)

VALUES (student_sequence.NEXTVAL, v_FirstName, v_LastName, v_NewMajor);

END IF;

END;

/

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Client-Server Model SQL results in many network trips,

one for each SQL statement PL/SQL permits several SQL

statements to be bundled into a single block

Results in fewer calls to database Less network traffic faster response time

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Features of PL / SQL Block Structure Error Handling Variables and Types Looping Constructs Cursors

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Features of PL / SQLBlock Structure

Basic unit of PL/SQL is a block Three possible sections of a block

Declarative section Executable section Exception handling

A block performs a logical unit of work in the program

Blocks can be nested

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Features of PL / SQLError Handling

Exception handling section permits the user to trap and respond to run-time errors

Exceptions can be associated with Predefined Oracle errors User-defined errors

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File Error.sqlIllustrates an exception handler

DECLARE

v_ErrorCode NUMBER; -- Code for the error

v_ErrorMsg VARCHAR2(200); -- Message text for the error

v_CurrentUser VARCHAR2(8); -- Current database user

v_Information VARCHAR2(100); -- Information about the error

BEGIN

/* Code which processes some data here */

NULL;

-- (continued)

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File Error.sqlIllustrates an exception handler

EXCEPTION

WHEN OTHERS THEN

v_ErrorCode := SQLCODE;

v_ErrorMsg := SQLERRM;

v_CurrentUser := USER;

v_Information := 'Error encountered on ' ||

TO_CHAR(SYSDATE) || ' by database user ' || v_CurrentUser;

INSERT INTO log_table (code, message, info)

VALUES (v_ErrorCode, v_ErrorMsg, v_Information);

END;

/

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Features of PL / SQLVariables and Types

A variable is a named location in memory that: can be read from assigned a value

Declared in the declaration section Variables have a specific type

associated with them Can be same type as database

columns

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Features of PL / SQLLooping Constructs

A loop allows execution of a set of statements repeatedly

Types of loops Simple loop Numeric For loop While loop

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File SimpleLoop.sqlDemonstrates a simple loop

DECLARE

v_LoopCounter BINARY_INTEGER := 1;

BEGIN

LOOP

INSERT INTO temp_table (num_col)

VALUES (v_LoopCounter);

v_LoopCounter := v_LoopCounter + 1;

EXIT WHEN v_LoopCounter > 50;

END LOOP;

END;

/

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File NumericLoop.sqlDemonstrates a numeric FOR loop

BEGIN

FOR v_LoopCounter IN 1..50 LOOP

INSERT INTO temp_table (num_col)

VALUES (v_LoopCounter);

END LOOP;

END;

/

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Features of PL / SQLCursors

A cursor creates a named context area as a result of executing an associated SQL statement

Permits the program to step through the multiple rows displayed by an SQL statement

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File CursorLoop.sqlDemonstrates a cursor fetch loop DECLARE

v_FirstName VARCHAR2(20);

v_LastName VARCHAR2(20);

CURSOR c_Students IS

SELECT first_name, last_name

FROM students;

BEGIN

OPEN c_Students;

LOOP

FETCH c_Students INTO v_FirstName, v_LastName;

EXIT WHEN c_Students%NOTFOUND;

/* Process data here */

END LOOP;

CLOSE c_Students;

END;

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File Conditional.sqlIllustrates a conditional statement DECLARE

v_TotalStudents NUMBER;

BEGIN

SELECT COUNT(*)

INTO v_TotalStudents

FROM students;

-- (continued)

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File Conditional.sqlIllustrates a conditional statement IF v_TotalStudents = 0 THEN

INSERT INTO temp_table (char_col)

VALUES ('There are no students registered');

ELSIF v_TotalStudents < 5 THEN

INSERT INTO temp_table (char_col)

VALUES ('There are only a few students registered');

ELSIF v_TotalStudents < 10 THEN

INSERT INTO temp_table (char_col)

VALUES ('There are a little more students registered');

ELSE

INSERT INTO temp_table (char_col)

VALUES ('There are many students registered');

END IF;

END;

/

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File PrintStudents.sqlIllustrates a stored procedure

CREATE OR REPLACE PROCEDURE PrintStudents(

p_Major IN students.major%TYPE) AS

CURSOR c_Students IS

SELECT first_name, last_name

FROM students

WHERE major = p_Major;

BEGIN

FOR v_StudentRec IN c_Students LOOP

DBMS_OUTPUT.PUT_LINE(v_StudentRec.first_name || ' ' ||

v_StudentRec.last_name);

END LOOP;

END;

/

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File PrintStudents.sqlIllustrates a stored procedure

BEGIN

PrintStudents ('Computer Science');

END;

/

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Online Code All of the named examples used in

the book are on the accompanying CD

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Example Tables / Views Tables used throughout text

classes – describes the classes available for the students to take

debug_table – used during debugging sessions log_table – records Oracle errors major_stats – holds statistics generated about

different majors registered_students – contains information

about the classes students are currently taking

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Example Tables / Views Tables used throughout text

rooms – holds information about the classrooms available

RS_audit – used to record changes made to registered students

student_sequence – generates unique values for the primary key of the students

students – contains information about students attending the school

temp_table – stores temporary data

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File tables.sqlPROMPT student_sequence...

DROP SEQUENCE student_sequence;

CREATE SEQUENCE student_sequence

START WITH 10000

INCREMENT BY 1;

PROMPT students table...

DROP TABLE students CASCADE CONSTRAINTS;

CREATE TABLE students (

id NUMBER(5) PRIMARY KEY,

first_name VARCHAR2(20),

last_name VARCHAR2(20),

major VARCHAR2(30),

current_credits NUMBER(3)

);

…

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Example TablesclassesCREATE TABLE classes( department CHAR (3), course NUMBER (3), description VARCHAR2 (2000),

max_students NUMBER (3),current_students NUMBER (3),num_credits NUMBER (1),room_id NUMBER (5),

CONSTRAINT classes_department_course PRIMARY KEY (department, course),CONSTRAINT classes_room_id FOREIGN KEY (room_id) REFERENCES rooms (room_id)

);

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Example Tablesdebug_table

CREATE TABLE debug_table( linecount NUMBER, debug_str VARCHAR2 (100));

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Example Tablesexception_view

CREATE VIEW exception_view AS SELECT exception exception_description, date_occurred FROM exception_table;

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Example Tableslog_table

CREATE TABLE log_table( code NUMBER, message VARCHAR2 (200), info VARCHAR2 (100));

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Example Tablesmajor_stats

CREATE TABLE major_stats( major VARCHAR2 (30), total_credits NUMBER, total_students NUMBER);

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Example Tablesregistered_studentsCREATE TABLE registered_students( student_id NUMBER (5) NOT NULL, department CHAR (3) NOT NULL, course NUMBER (3) NOT NULL, grade CHAR (1), CONSTRAINT rs_grade CHECK (grade IN ('A', 'B', 'C', 'D', 'E')), CONSTRAINT rs_student_id FOREIGN KEY (student_id) REFERENCES students (id), CONSTRAINT rs_department_course FOREIGN KEY (department, course) REFERENCES classes (department, course));

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Example Tablesrooms

CREATE TABLE rooms( room_id NUMBER (5) PRIMARY KEY, building VARCHAR2 (15), room_number NUMBER (4), number_seats NUMBER (4), description VARCHAR2 (50));

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Example TablesRS_auditCREATE TABLE RS_audit( change_type CHAR (1) NOT NULL, changed_by VARCHAR2 (8) NOT NULL, timestamp DATE NOT NULL, old_student_id NUMBER (5), old_department CHAR (3), old_course NUMBER (3), old_grade CHAR (1), new_student_id NUMBER (5), new_department CHAR (3), new_course NUMBER (3), new_grade CHAR (1));

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Example Tablesstudent_sequence

CREATE SEQUENCE student_sequence

START WITH 10000

INCREMENT BY 1;

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Example Tablesstudents

CREATE TABLE students( id NUMBER(5) PRIMARY KEY, first_name VARCHAR2 (20), last_name VARCHAR2 (20), major VARCHAR2 (30), current_credits NUMBER(3));

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Example Tablestemp_table

CREATE TABLE temp_table(

num_col NUMBER,char_col VARCHAR2 (60)

);

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In Conclusion PL/SQL is a sophisticated

programming language used to access an Oracle database

Procedural constructs are integrated seamlessly with SQL, resulting in a structured, powerful language

Combines flexibility of SQL with the configure ability of a 3GL