1. ISYS 365 – SQL*Plus Environment

2. Agenda What is SQL*Plus? Command Line Editor Useful SQL*Plus Commands
Useful System Tables
What is PL/SQL?
PL/SQL Constructs

3. 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

4. Command Line Editor list or list # change del
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

5. Command Line Editor append input
Places text at the end of the current line without any spaces between the existing text & the appended text
input

6. 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

7. 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 (set the width of the column Item to 18 characters
column Rate format 90.99
zero tells SQL*Plus to pad the number with a zero (if necessary)
999,999,
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

8. 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

9. 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

10. 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

11. Break on Example
BREAK ON DEPARTMENT_ID SKIP PAGE ON JOB_ID SKIP 1 ON SALARY SKIP 1
SELECT DEPARTMENT_ID, JOB_ID, SALARY, LAST_NAME FROM EMP_DETAILS_VIEW WHERE SALARY > ORDER BY DEPARTMENT_ID, JOB_ID, SALARY, LAST_NAME;
All rows with the same DEPARTMENT_ID print together on one page, and within that page all rows with the same JOB_ID print in groups. Within each group of jobs, those jobs with the same SALARY print in groups. Breaks in LAST_NAME cause no action because LAST_NAME does not appear in the BREAK command.

12. 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

13. 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)

14. Oracle spool tips
The SPOOL command causes SQL*Plus to write the results to a file on the operating system.
SQL> spool myfile.lst
SQL> spool off;
if you spool out a file that does not exist, SQL*Plus creates a new file.  SQL*Plus replaces the existing file if the file name already exists.  In Oracle 10g, the SPOOL command has a new APPEND option.  Now, you can append new SQL*Plus output in an existing file. 

15. 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

16. Useful SQL*Plus Commands
To clear the current settings
ttitle off
btitle off
clear columns
clear breaks
clear computes

17. Useful System Tables User_Constraints User_Cons_Columns
Useful fields: constraint_name, table_name, constraint_type
constraint_type: C (Check Constraint on a table), P (Primary Key), R (Referential Integrity) & U (Unique)
User_Cons_Columns
Useful fields: constraint_name, column_name, position
SELECT column_name
FROM user_cons_columns
WHERE constraint_name=‘SYS_C ’;
Retrieving constraints defined by the user
WHERE CONSTRAINT_NAME NOT LIKE '%SYS%';

18. Useful System Tables user_sequences user_errors
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

19. Creating a Sequence: Example
CREATE SEQUENCE customers_seq START WITH 1000 INCREMENT BY 1

20. 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

21. PL/SQL Constructs PL/SQL based on Ada language constructs
Block Structure
Error Handling
Variables and Types
Conditionals
Looping Constructs
Cursors

22. Introduction to PL / SQL

23. 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

24. File 3gl_4gl.sql Demonstrates 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; /
%NOTFOUND: this attribute yields the number of rows affected by am INSERT, UPDDATE or DELETE statement affected no rows, or a SELECT INTO statement returned no rows. Otherwise it yields FALSE

25. 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

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

27. Features of PL / SQL Block 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

28. Features of PL / SQL Error 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

29. File Error.sql Illustrates 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)

30. File Error.sql Illustrates an exception handler
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; /

31. SQLCODE, SQLERRM
SQLCODE is only useful in an exception handler. Othside a handler SQLCODE always returns 0, it let you identify which internal exception was raised. You can’t use SQLCODE directly in a SQL statement. Assign the value of SQLCODE to a local variable first
The function SQLERRM returns the error message associated with its error-number argument. If the argument is omitted, it returns the error message associated with the current value of SQLCODE

32. Features of PL / SQL Variables 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

33. Features of PL / SQL Looping Constructs
A loop allows execution of a set of statements repeatedly
Types of loops
Simple loop
Numeric For loop
While loop

34. File SimpleLoop.sql Demonstrates 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; /

35. File NumericLoop.sql Demonstrates a numeric FOR loop
BEGIN
FOR v_LoopCounter IN LOOP
INSERT INTO temp_table (num_col)
VALUES (v_LoopCounter);
END LOOP;
END; /

36. Features of PL / SQL Cursors
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

37. File CursorLoop.sql Demonstrates 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;

38. File Conditional.sql Illustrates a conditional statement
DECLARE
v_TotalStudents NUMBER;
BEGIN
SELECT COUNT(*)
INTO v_TotalStudents
FROM students;
-- (continued)

39. File Conditional.sql Illustrates 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
VALUES ('There are only a few students registered');
ELSIF v_TotalStudents < 10 THEN
VALUES ('There are a little more students registered');
ELSE
VALUES ('There are many students registered');
END IF;
END; /

40. File PrintStudents.sql Illustrates 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; /

41. File PrintStudents.sql Illustrates a stored procedure
BEGIN
PrintStudents ('Computer Science');
END; /

42. 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

43. 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

44. File tables.sql PROMPT 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) ); …

45. Example Tables classes
CREATE 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) );

46. Example Tables debug_table
CREATE TABLE debug_table (
linecount NUMBER,
debug_str VARCHAR2 (100) );

47. Example Tables exception_view
CREATE VIEW exception_view AS
SELECT exception exception_description,
date_occurred
FROM exception_table;

48. Example Tables log_table
CREATE TABLE log_table (
code NUMBER,
message VARCHAR2 (200),
info VARCHAR2 (100) );

49. Example Tables major_stats
CREATE TABLE major_stats (
major VARCHAR2 (30),
total_credits NUMBER,
total_students NUMBER );

50. Example Tables registered_students
CREATE 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) );

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

52. Example Tables RS_audit
CREATE 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) );

53. Example Tables student_sequence
CREATE SEQUENCE student_sequence
START WITH 10000
INCREMENT BY 1;

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

55. Example Tables temp_table
CREATE TABLE temp_table (
num_col NUMBER,
char_col VARCHAR2 (60) );

56. 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