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Friday, March 29, 2013

Orace CREATE PACKAGE

Use the CREATE PACKAGE statement to create the specification for a stored package, which is an encapsulated collection of related procedures, functions, and other program objects stored together in the database. The package specification declares these objects. The package body, specified subsequently, defines these objects.

Prerequisites

Before a package can be created, the user SYS must run a SQL script commonly called DBMSSTDX.SQL. The exact name and location of this script depend on your operating system.

To create a package in your own schema, you must have the CREATE PROCEDURE system privilege. To create a package in another user's schema, you must have the CREATE ANY PROCEDURE system privilege.

To embed a CREATE PACKAGE statement inside an Oracle Database precompiler program, you must terminate the statement with the keyword END-EXEC followed by the embedded SQL statement terminator for the specific language.

OR REPLACE

Specify OR REPLACE to re-create the package specification if it already exists. Use this clause to change the specification of an existing package without dropping, re-creating, and regranting object privileges previously granted on the package. If you change a package specification, then Oracle Database recompiles it.

Users who had previously been granted privileges on a redefined package can still access the package without being regranted the privileges.

If any function-based indexes depend on the package, then the database marks the indexes DISABLED.

Package Speccification

Specify the package specification, which can contain type definitions, cursor declarations, variable declarations, constant declarations, exception declarations, PL/SQL subprogram specifications, and call specifications, which are declarations of a C or Java routine expressed in PL/SQL.

Examples:

The following SQL statement creates the specification of the emp_mgmt package.

CREATE OR REPLACE PACKAGE emp_mgmt AS 
   FUNCTION hire (last_name VARCHAR2, job_id VARCHAR2, 
      manager_id NUMBER, salary NUMBER, 
      commission_pct NUMBER, department_id NUMBER) 
      RETURN NUMBER; 
   FUNCTION create_dept(department_id NUMBER, location_id NUMBER) 
      RETURN NUMBER; 
   PROCEDURE remove_emp(employee_id NUMBER); 
   PROCEDURE remove_dept(department_id NUMBER); 
   PROCEDURE increase_sal(employee_id NUMBER, salary_incr NUMBER); 
   PROCEDURE increase_comm(employee_id NUMBER, comm_incr NUMBER); 
   no_comm EXCEPTION; 
   no_sal EXCEPTION; 
END emp_mgmt; 
/ 

The specification for the emp_mgmt package declares the following public program objects:

  • The functions hire and create_dept.
  • The procedures remove_emp, remove_dept, increase_sal, and increase_comm.
  • The exceptions no_comm and no_sal.

Before you can call this package's procedures and functions, you must define these procedures and functions in the package body. For an example of a CREATE PACKAGE BODY statement that creates the body of the emp_mgmt package.

CREATE PACKAGE BODY

Use the CREATE PACKAGE BODY statement to create the body of a stored package, which is an encapsulated collection of related procedures, stored functions, and other program objects stored together in the database. The package body defines these objects. The package specification, defined in an earlier CREATE PACKAGE statement, declares these objects.

Example:

CREATE OR REPLACE PACKAGE BODY emp_mgmt AS 
   tot_emps NUMBER; 
   tot_depts NUMBER; 
FUNCTION hire 
   (last_name VARCHAR2, job_id VARCHAR2, 
    manager_id NUMBER, salary NUMBER, 
    commission_pct NUMBER, department_id NUMBER) 
   RETURN NUMBER IS new_empno NUMBER; 
BEGIN 
   SELECT employees_seq.NEXTVAL 
      INTO new_empno 
      FROM DUAL; 
   INSERT INTO employees 
      VALUES (new_empno, 'First', 'Last','first.last@oracle.com', 
              '(123)123-1234','18-JUN-02','IT_PROG',90000000,00, 
              100,110); 
      tot_emps := tot_emps + 1; 
   RETURN(new_empno); 
END; 
FUNCTION create_dept(department_id NUMBER, location_id NUMBER) 
   RETURN NUMBER IS 
      new_deptno NUMBER; 
   BEGIN 
      SELECT departments_seq.NEXTVAL 
         INTO new_deptno 
         FROM dual; 
      INSERT INTO departments 
         VALUES (new_deptno, 'department name', 100, 1700); 
      tot_depts := tot_depts + 1; 
      RETURN(new_deptno); 
   END; 
PROCEDURE remove_emp (employee_id NUMBER) IS 
   BEGIN 
      DELETE FROM employees 
      WHERE employees.employee_id = remove_emp.employee_id; 
      tot_emps := tot_emps - 1; 
   END; 
PROCEDURE remove_dept(department_id NUMBER) IS 
   BEGIN 
      DELETE FROM departments 
      WHERE departments.department_id = remove_dept.department_id; 
      tot_depts := tot_depts - 1; 
      SELECT COUNT(*) INTO tot_emps FROM employees; 
   END; 
PROCEDURE increase_sal(employee_id NUMBER, salary_incr NUMBER) IS 
   curr_sal NUMBER; 
   BEGIN 
      SELECT salary INTO curr_sal FROM employees 
      WHERE employees.employee_id = increase_sal.employee_id; 
      IF curr_sal IS NULL 
         THEN RAISE no_sal; 
      ELSE 
         UPDATE employees 
         SET salary = salary + salary_incr 
         WHERE employee_id = employee_id; 
      END IF; 
   END; 
PROCEDURE increase_comm(employee_id NUMBER, comm_incr NUMBER) IS 
   curr_comm NUMBER; 
   BEGIN 
      SELECT commission_pct 
      INTO curr_comm 
      FROM employees 
      WHERE employees.employee_id = increase_comm.employee_id; 
      IF curr_comm IS NULL 
         THEN RAISE no_comm; 
      ELSE 
         UPDATE employees 
         SET commission_pct = commission_pct + comm_incr; 
      END IF; 
   END; 
END emp_mgmt; 
/ 

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