Creating packages v17

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A package isn't an executable piece of code but a repository of code. When you use a package, you execute or make reference to an element within a package.

Creating the package specification

The package specification contains the definition of all the elements in the package that you can reference from outside of the package. These are called the public elements of the package, and they act as the package interface. The following code sample is a package specification:

--
-- Package specification for the 'emp_admin' package.
--
CREATE OR REPLACE PACKAGE emp_admin
IS
   FUNCTION get_dept_name (
      p_deptno NUMBER DEFAULT 10
   )
   RETURN VARCHAR2;
   FUNCTION update_emp_sal (
      p_empno NUMBER,
      p_raise NUMBER
   )
   RETURN NUMBER;
   PROCEDURE hire_emp (
      p_empno           NUMBER,
      p_ename           VARCHAR2,
      p_job             VARCHAR2,
      p_sal             NUMBER,
      p_hiredate        DATE      DEFAULT   sysdate,
      p_comm            NUMBER    DEFAULT   0,
      p_mgr             NUMBER,
      p_deptno          NUMBER    DEFAULT   10
   );
   PROCEDURE fire_emp (
      p_empno NUMBER
   );
END emp_admin;

This code sample creates the emp_admin package specification. This package specification consists of two functions and two stored procedures. You can also add the OR REPLACE clause to the CREATE PACKAGE statement for convenience.

Creating the package body

The body of the package contains the actual implementation behind the package specification. For the emp_admin package specification in the example, this code now create a package body that implements the specifications. The body contains the implementation of the functions and stored procedures in the specification.

--
--  Package body for the 'emp_admin' package.
--
CREATE OR REPLACE PACKAGE BODY emp_admin
IS
   --
   --  Function that queries the 'dept' table based on the department
   --  number and returns the corresponding department name.
   --
   FUNCTION get_dept_name (
      p_deptno        IN NUMBER DEFAULT 10
   )
   RETURN VARCHAR2
   IS
      v_dname         VARCHAR2(14);
   BEGIN
      SELECT dname INTO v_dname FROM dept WHERE deptno = p_deptno;
      RETURN v_dname;
   EXCEPTION
      WHEN NO_DATA_FOUND THEN
         DBMS_OUTPUT.PUT_LINE('Invalid department number ' || p_deptno);
         RETURN '';
   END;
   --
   --  Function that updates an employee's salary based on the
   --  employee number and salary increment/decrement passed
   --  as IN parameters.  Upon successful completion the function
   --  returns the new updated salary.
   --
   FUNCTION update_emp_sal (
      p_empno         IN NUMBER,
      p_raise         IN NUMBER
   )
   RETURN NUMBER
   IS
      v_sal           NUMBER := 0;
   BEGIN
      SELECT sal INTO v_sal FROM emp WHERE empno = p_empno;
      v_sal := v_sal + p_raise;
      UPDATE emp SET sal = v_sal WHERE empno = p_empno;
      RETURN v_sal;
   EXCEPTION
      WHEN NO_DATA_FOUND THEN
         DBMS_OUTPUT.PUT_LINE('Employee ' || p_empno || ' not found');
         RETURN -1;
      WHEN OTHERS THEN
         DBMS_OUTPUT.PUT_LINE('The following is SQLERRM:');
         DBMS_OUTPUT.PUT_LINE(SQLERRM);
         DBMS_OUTPUT.PUT_LINE('The following is SQLCODE:');
         DBMS_OUTPUT.PUT_LINE(SQLCODE);
         RETURN -1;
   END;
   --
   --  Procedure that inserts a new employee record into the 'emp' table.
   --
   PROCEDURE hire_emp (
      p_empno         NUMBER,
      p_ename         VARCHAR2,
      p_job           VARCHAR2,
      p_sal           NUMBER,
      p_hiredate      DATE    DEFAULT sysdate,
      p_comm          NUMBER  DEFAULT 0,
      p_mgr           NUMBER,
      p_deptno        NUMBER  DEFAULT 10
   )
   AS
   BEGIN
      INSERT INTO emp(empno, ename, job, sal, hiredate, comm, mgr, deptno)
         VALUES(p_empno, p_ename, p_job, p_sal,
                p_hiredate, p_comm, p_mgr, p_deptno);
   END;
   --
   --  Procedure that deletes an employee record from the 'emp' table based
   --  on the employee number.
   --
   PROCEDURE fire_emp (
      p_empno         NUMBER
   )
   AS
   BEGIN
      DELETE FROM emp WHERE empno = p_empno;
   END;
END;
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