Oracle db subprograms
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Transcript of Oracle db subprograms
Agenda• PL/SQL Units
• Anonymous Block
• Stroed PL/SQL Units
• PL/SQL Packages
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)
PL/SQL Units
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
Anonymous Block
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.
Anonymous block Example -SimpleDECLARE
last_name VARCHAR2(10);cursor c1 IS
SELECT LAST_NAMEFROM EMPLOYEES
WHERE DEPARTMENT_ID = 20ORDER BY LAST_NAME;
BEGINOPEN c1;LOOP
FETCH c1 INTO last_name;EXIT WHEN c1%NOTFOUND;DBMS_OUTPUT.PUT_LINE(last_name);
END LOOP;END;
Anonymous block Example -Exception HandlerDECLARE
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;
Anonymous block Example -User-Defined ExceptionDECLARE
Emp_name VARCHAR2(10);Emp_number INTEGER;Empno_out_of_range EXCEPTION;
BEGINEmp_number := 10001;IF Emp_number > 9999 OR Emp_number < 1000 THEN
RAISE Empno_out_of_range;ELSE
SELECT LAST_NAME INTO Emp_nameFROM EMPLOYEES
WHERE EMPLOYEE_ID = Emp_number;DBMS_OUTPUT.PUT_LINE('Employee name is ' ||
Emp_name);END IF;
EXCEPTIONWHEN Empno_out_of_range THEN
DBMS_OUTPUT.PUT_LINE('Employee number ' || Emp_number || ' is out of range.');END;
Stored PL/SQL Units
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.
Stored Procedure with ParametersCREATE OR REPLACE PROCEDURE get_emp_names (dept_num IN NUMBER ) ISemp_name VARCHAR2(10);CURSOR c1 (dept_num NUMBER) IS
SELECT LAST_NAME FROM EMPLOYEESWHERE DEPARTMENT_ID = dept_num;
BEGINOPEN c1(dept_num);LOOP
FETCH c1 INTO emp_name;EXIT WHEN C1%NOTFOUND;DBMS_OUTPUT.PUT_LINE(emp_name);
END LOOP;CLOSE c1;
END;
Stored Procedure with%TYPE and %ROWTYPECREATE 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;
FunctionCREATE 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;
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;
PL/SQL Packages
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.
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.
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;
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;
Package Body – Example IIPROCEDURE 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;
Invoke package proceduresDECLARE
empno NUMBER(6);
sal NUMBER(6);
temp NUMBER(6);
BEGIN
empno := employee_management.hire_emp(
'John', 'Doe', '[email protected]', '555-0100',
'20-SEP-07', 'ST_CLERK', 2500, 0, 100, 20);
DBMS_OUTPUT.PUT_LINE(
'New employee ID is ' || TO_CHAR(empno));
END;
Q & A
