This document provides an overview of PL/SQL subprograms, including anonymous blocks, stored PL/SQL units like procedures and functions, and PL/SQL packages. It defines each component and provides examples. Anonymous blocks allow executing PL/SQL code without a name. Stored procedures and functions can be invoked by many users. Packages organize related objects and allow overloading subprograms. The document demonstrates package specifications that declare objects and package bodies that define objects and private components.

1. Oracle DB
Subprograms
Simon Huang
simon581923@gmail.com

2. Agenda
• PL/SQL Units
• Anonymous Block
• Stroed PL/SQL Units
• PL/SQL Packages

3. 參考文件
• Oracle Database Documentation Library
 http://www.oracle.com/pls/db112/homepage
• E25519
 Oracle Database PL/SQL Language Reference 11g Release 2 (11.2)
• E41502
 Oracle Database Advanced Application Developer's Guide 11g Release 2
(11.2)

4. PL/SQL Units

5. PL/SQL Units
• PL/SQL is a modern, block-structured programming
language. PL/SQL provides procedural constructs, such
as loops and conditional statements, that are not
available in standard SQL.
• You can directly enter SQL data manipulation language
(DML) statements inside PL/SQL blocks, and you can
use subprograms supplied by Oracle to perform data
definition language (DDL) statements.
• PL/SQL Units include
 Anonymous Blocks
 Stored PL/SQL Units
 Triggers

6. Anonymous Block

7. Anonymous block
• An anonymous block is a PL/SQL unit that has no name.
• An anonymous block consists of
 An optional declarative part
 An executable part
 And one or more optional exception handlers.
• The declarative part declares
 PL/SQL variables
 Exceptions handlers
 Cursors
• The executable part contains
 PL/SQL code
 SQL statements
 And can contain nested blocks.
• Exception handlers contain code that is invoked when the exception
is raised, either as a predefined PL/SQL exception (such as
NO_DATA_FOUND or ZERO_DIVIDE) or as an exception that you
define.

8. Anonymous block Example -
Simple
DECLARE
last_name VARCHAR2(10);
cursor c1 IS
SELECT LAST_NAME
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 20
ORDER BY LAST_NAME;
BEGIN
OPEN c1;
LOOP
FETCH c1 INTO last_name;
EXIT WHEN c1%NOTFOUND;
DBMS_OUTPUT.PUT_LINE(last_name);
END LOOP;
END;

9. Anonymous block Example -
Exception Handler
DECLARE
Emp_number INTEGER := 9999;
Emp_name VARCHAR2(10);
BEGIN
SELECT LAST_NAME INTO Emp_name
FROM EMPLOYEES
WHERE EMPLOYEE_ID = Emp_number;
DBMS_OUTPUT.PUT_LINE('Employee name is '
|| Emp_name);
EXCEPTION
WHEN NO_DATA_FOUND THEN
DBMS_OUTPUT.PUT_LINE('No such employee: '
|| Emp_number);
END;

10. Anonymous block Example -
User-Defined Exception
DECLARE
Emp_name VARCHAR2(10);
Emp_number INTEGER;
Empno_out_of_range EXCEPTION;
BEGIN
Emp_number := 10001;
IF Emp_number > 9999 OR Emp_number < 1000 THEN
RAISE Empno_out_of_range;
ELSE
SELECT LAST_NAME INTO Emp_name
FROM EMPLOYEES
WHERE EMPLOYEE_ID = Emp_number;
DBMS_OUTPUT.PUT_LINE('Employee name is ' ||
Emp_name);
END IF;
EXCEPTION
WHEN Empno_out_of_range THEN
DBMS_OUTPUT.PUT_LINE('Employee number ' ||
Emp_number || ' is out of range.');
END;

11. Stored PL/SQL
Units

12. Stored PL/SQL Units
• A stored PL/SQL unit is a subprogram (procedure or
function) or package that:
 Has a name.
 Can take parameters, and can return values.
 Is stored in the data dictionary.
 Can be invoked by many users.
• If a subprogram belongs to a package, it is called a
package subprogram; if not, it is called a standalone
subprogram.

13. Stored Procedure with
Parameters
CREATE OR REPLACE PROCEDURE get_emp_names (
dept_num IN NUMBER ) IS
emp_name VARCHAR2(10);
CURSOR c1 (dept_num NUMBER) IS
SELECT LAST_NAME FROM EMPLOYEES
WHERE DEPARTMENT_ID = dept_num;
BEGIN
OPEN c1(dept_num);
LOOP
FETCH c1 INTO emp_name;
EXIT WHEN C1%NOTFOUND;
DBMS_OUTPUT.PUT_LINE(emp_name);
END LOOP;
CLOSE c1;
END;

14. Stored Procedure with
%TYPE and %ROWTYPE
CREATE OR REPLACE PROCEDURE get_emp_rec (
emp_number IN EMPLOYEES.EMPLOYEE_ID%TYPE,
emp_info OUT EMPLOYEES%ROWTYPE) IS
BEGIN
SELECT * INTO emp_info
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_number;
END;

15. Function
CREATE FUNCTION get_bal(acc_no IN NUMBER)
RETURN NUMBER
IS acc_bal NUMBER(11,2);
BEGIN
SELECT order_total
INTO acc_bal
FROM orders
WHERE customer_id = acc_no;
RETURN(acc_bal);
END;

16. 執行Procedure & Function
• EXEC get_emp_names(10);
• VARIABLE emp_info EMPLOYEES%ROWTYPE;
• EXEC get_emp_rec( 7369, : emp_info);
• SELECT get_bal(165) FROM DUAL;

17. PL/SQL Packages

18. PL/SQL Packages - Concept
• A package is a collection of related program objects (for
example, subprogram, variables, constants, cursors, and
exceptions) stored as a unit in the database.
• Packages is an alternative to creating subprograms as
standalone schema objects.
• Packages have many advantages over standalone
subprograms. For example, they:
 Let you organize your application development more efficiently.
 Let you grant privileges more efficiently.
 Let you modify package objects without recompiling dependent
schema objects.
 Enable Oracle Database to read multiple package objects into
memory at once.
 Can contain global variables and cursors that are available to all
subprograms in the package.
 Let you overload subprograms. Overloading a subprogram means
creating multiple subprograms with the same name in the same
package, each taking arguments of different number or data type.

19. PL/SQL Packages - Concept
• A package include two parts: the specification part and
the body of a package.
• The specification part of a package declares the public
types, variables, constants, and subprograms that are
visible outside the immediate scope of the package.
• The body of a package defines both the objects declared
in the specification and private objects that are not
visible to applications outside the package.

20. Package Specification -
Example
-- Package specification:
CREATE or REPLACE PACKAGE employee_management IS
FUNCTION hire_emp (
firstname VARCHAR2,
lastname VARCHAR2,
email VARCHAR2,
phone VARCHAR2,
hiredate DATE,
job VARCHAR2,
sal NUMBER,
comm NUMBER,
mgr NUMBER,
deptno NUMBER
) RETURN NUMBER;
PROCEDURE fire_emp(
emp_id IN NUMBER
);
PROCEDURE sal_raise (
emp_id IN NUMBER,
sal_incr IN NUMBER
);
END employee_management;

21. Package Body – Example I
-- Package body:
CREATE or REPLACE PACKAGE BODY employee_management IS
FUNCTION hire_emp (
firstname VARCHAR2,
lastname VARCHAR2,
email VARCHAR2,
phone VARCHAR2,
hiredate DATE,
job VARCHAR2,
sal NUMBER,
comm NUMBER,
mgr NUMBER,
deptno NUMBER
) RETURN NUMBER IS
new_empno NUMBER(10);
BEGIN
new_empno := emp_sequence.NEXTVAL;
INSERT INTO EMPLOYEES (
employee_id, first_name, last_name, email, phone_number, hire_date,
job_id, salary, commission_pct, manager_id, department_id)
VALUES (
new_empno, firstname, lastname, email, phone, hiredate,
job, sal, comm, mgr, deptno);
RETURN (new_empno);
END hire_emp;

22. Package Body – Example II
PROCEDURE fire_emp (
emp_id IN NUMBER) IS
BEGIN
DELETE FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;
IF SQL%NOTFOUND THEN
raise_application_error(
-20011, 'Invalid Employee Number: ‘ || TO_CHAR(Emp_id));
END IF;
END fire_emp;
PROCEDURE sal_raise (
emp_id IN NUMBER,
sal_incr IN NUMBER) IS
BEGIN
UPDATE EMPLOYEES
SET SALARY = SALARY + sal_incr
WHERE EMPLOYEE_ID = emp_id;
IF SQL%NOTFOUND THEN
raise_application_error(
-20011, 'Invalid Employee Number: ‘ || TO_CHAR(Emp_id));
END IF;
END sal_raise;
END employee_management;

23. Invoke package procedures
DECLARE
empno NUMBER(6);
sal NUMBER(6);
temp NUMBER(6);
BEGIN
empno := employee_management.hire_emp(
'John', 'Doe', 'john.doe@company.com', '555-0100',
'20-SEP-07', 'ST_CLERK', 2500, 0, 100, 20);
DBMS_OUTPUT.PUT_LINE(
'New employee ID is ' || TO_CHAR(empno));
END;

24. Q & A