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