Package - pl/sql programming, PL-SQL Programming

What Is a Package?

The package is a schema object that group logically related PL/SQL items, types, and subprograms. The Packages usually have 2 parts, a specification & a body, though many times the body is needless. The specification is the interface to your applications; it declares the type, constants, variables, exceptions, cursors, and subprograms accessible for use. The body fully defines the cursors & subprograms, and so equipment the specification.

The figure shows, the specification as an operational interface and of the body as the "black box." You can enhance, debug, or replace the package body without changing the interface to the package.

1715_package.png

Figure: Package Interface

To build packages, use the CREATE PACKAGE statement that you can execute interactively from the SQL Plus. The syntax for the same is as shown:

CREATE [OR REPLACE] PACKAGE package_name

[AUTHID {CURRENT_USER | DEFINER}] {IS | AS}

[type_definition [type_definition] ...]

[cursor_spec [cursor_spec] ...]

[item_declaration [item_declaration] ...]

[{subprogram_spec | call_spec} [{subprogram_spec | call_spec}]...]

END [package_name];

[CREATE [OR REPLACE] PACKAGE BODY package_name {IS | AS}

[type_definition [type_definition] ...]

[cursor_body [cursor_body] ...]

[item_declaration [item_declaration] ...]

[{subprogram_spec | call_spec} [{subprogram_spec | call_spec}]...]

[BEGIN

sequence_of_statements]

END [package_name];]

The specifications hold the public declarations that are visible to your application. The body holds the implementation details and private declarations that are hidden from your application. The declarative section below of the package body is the optional initialization section that typically holds the statements that initialize the package variables. The AUTHID clause determine whether all the packaged subprograms execute with the privileges of their definer or invoker, and whether their unqualified references to schema objects are solved in the schema of the definer or invoker.

The call specification publishes a Java method or external C function in the Oracle data dictionary. The call specification publishes the routine by mapping its parameter types, name, and return type to their SQL counterparts.

In the illustration below, you package a cursor, a record type, and two employment procedures. Note that the procedure hire_employee uses the database series empno_seq and the function SYSDATE to insert a new employee number & hire date, correspondingly.

CREATE OR REPLACE PACKAGE emp_actions AS -- spec

TYPE EmpRecTyp IS RECORD (emp_id INTEGER, salary REAL);

CURSOR desc_salary RETURN EmpRecTyp;

PROCEDURE hire_employee (

ename VARCHAR2,

job VARCHAR2,

mgr NUMBER,

sal NUMBER,

comm NUMBER,

deptno NUMBER);

PROCEDURE fire_employee (emp_id NUMBER);

END emp_actions;

CREATE OR REPLACE PACKAGE BODY emp_actions AS -- body

CURSOR desc_salary RETURN EmpRecTyp IS

SELECT empno, sal FROM emp ORDER BY sal DESC;

PROCEDURE hire_employee (

ename VARCHAR2,

job VARCHAR2,

mgr NUMBER,

sal NUMBER,

comm NUMBER,

deptno NUMBER) IS

BEGIN

INSERT INTO emp VALUES (empno_seq.NEXTVAL, ename, job,

mgr, SYSDATE, sal, comm, deptno);

END hire_employee;

PROCEDURE fire_employee (emp_id NUMBER) IS

BEGIN

DELETE FROM emp WHERE empno = emp_id;

END fire_employee;

END emp_actions;

The declarations in the package specification are only visible & accessible to the applications.

The Implementation details in the package body are hidden and inaccessible. Therefore, you can change the body without having to recompile the calling programs.

Posted Date: 10/5/2012 5:58:18 AM | Location : United States







Related Discussions:- Package - pl/sql programming, Assignment Help, Ask Question on Package - pl/sql programming, Get Answer, Expert's Help, Package - pl/sql programming Discussions

Write discussion on Package - pl/sql programming
Your posts are moderated
Related Questions
Create a Oracle procedure to produce vertical output format when selecting rows from a database table.

Question 1. Update stock levels when the order is cancelled At times, customers make mistakes in submitting their orders and call to cancel the order. Brewbean’s wants to create a

COSMOZOI C THEORY - Richter (1865) proposed the cosmozoic theory that says that life came by spores (cosmozoa) or other particles from other planets on the earth.

Implicit Rollbacks Before execute the INSERT, UPDATE, or DELETE statement, the Oracle marks an implicit savepoint . When the statement fails, the Oracle rolls back to the save

Updating by replacement Syntax: UPDATE ENROLMENT SET Name = 'Ann' WHERE StudentId = SID ('S1'); Note the use of SET, as already noted in connection with direct a

Explicit Cursors The set of rows returned by the query can include zero, one, or multiple rows, depending on how many rows meet your search criteria. Whenever a query returns

Operators on Tables and Rows Row Extraction TUPLE FROM r, SQL has row subqueries. These are just like scalar subqueries except that they may specify more than one column.

Use of COUNT in SQL It describes and discusses various general methods of expressing constraints, eventually noting that support for "=" with relation operands is sufficient f

Using FIRST and LAST FIRST and LAST return the first and last (minimum and maximum) index numbers in a collection. When the collection is empty, the FIRST and LAST return NULL

Use Serially Reusable Packages To help you to manage the use of memory, the PL/SQL gives the pragma SERIALLY_ REUSABLE that mark some packages as serially reusable . So mark