Chapter -09 Creating Procedures 03

Passing Actula Parameters:Creating the add_dept Procedure

CREATE OR REPLACE PROCEDURE add_dept
(
        p_name IN dept.department_name%TYPE,
        p_loc  IN dept.location_id%TYPE
)
IS
BEGIN
        INSERT INTO dept(department_id,department_name,location_id)
        VALUES(departments_seq.NEXTVAL,p_name,p_loc);

        COMMIT;
END add_dept;
/
SQL> begin
  2  add_dept('ORACLE',1700);
  3  end;
  4  /

PL/SQL procedure successfully completed.

Passing Actual Parameters:Examples

--Passing parameters using the postional notation.

EXECUTE add_dept('TRAINING',2500);

 

--Passing parameters using the named notation.

EXECUTE add_dept(p_loc=>2400,p_name=>'EDUCATION');

Using the DEFAULT Option for the Parameters

• Define default values for parameters
• Provides flexibility by combining the postion and named parameter-passing syntax

CREATE OR REPLACE PROCEDURE add_dept_withdefault
(
        p_name  dept.department_name%TYPE:='Unknow',
        p_loc   dept.location_id%TYPE DEFAULT 1700
)
IS
BEGIN
        INSERT INTO dept(department_id,department_name,location_id)
        VALUES(departments_seq.NEXTVAL,p_name,p_loc);

        COMMIT;
END add_dept_withdefault;
/
SQL> EXECUTE add_dept_withdefault

PL/SQL procedure successfully completed.

SQL> EXECUTE add_dept_withdefault('ADVERTISING',p_loc=>1200);

PL/SQL procedure successfully completed.

SQL> EXECUTE add_dept_withdefault(p_loc=>1200);

PL/SQL procedure successfully completed.

Calling Procedures

• You can call procedures using anonymous blocks,another procedure,or packages.
• You must own the procedure or have the EXECUTE privilege.

CREATE OR REPLACE PROCEDURE process_emp
IS
        CURSOR cur_emp_cursor IS
                SELECT employee_id FROM emp;
BEGIN
        FOR emp_rec IN cur_emp_cursor
        LOOP
                raise_salary(emp_rec.employee_id,10);
        END LOOP;
        COMMIT;
END process_emp;
/

Forward Declaration

• If nested subprograms in the same PL/SQL block invoke each other,then one requries a forward declaration,because a subprogram must be declared before it can be invoked.
• A  forward declaration declares a nested subprogram but does not define it.You must define it later in the same block.The forward declaration and the definition must have the same subprogram heading.

DECLARE
        PROCEDURE proc1(number1 NUMBER);

        PROCEDURE proc2(number2 NUMBER) IS
        BEGIN
                proc1(number2);
        END;

        PROCEDURE proc1(number1 NUMBER) IS
        BEGIN
                proc2(number1);
        END;
BEGIN
        NULL
END;
/

Handled Exceptions

Handled Exceptions:Example

CREATE OR REPLACE PROCEDURE add_department_a
(
        p_name  VARCHAR2,
        p_mgr   NUMBER,
        p_loc   NUMBER
)
IS
BEGIN
        INSERT INTO DEPARTMENTS(department_id,department_name,manager_id,location_id)
        VALUES(DEPARTMENTS_SEQ.NEXTVAL,p_name,p_mgr,p_loc);

        DBMS_OUTPUT.PUT_LINE('Added Dept:' || p_name);

EXCEPTION
        WHEN OTHERS THEN
                DBMS_OUTPUT.PUT_LINE('Err:adding dept:' || p_name);
END;

/

CREATE OR REPLACE PROCEDURE create_dept_a
IS
BEGIN
        add_department_a('Media',100,1800);
        add_department_a('Editing',99,1800);
        add_department_a('Advertising',101,1800);
END;
/

SQL> begin
  2  create_dept_a;
  3  end;
  4  /
Added Dept:Media
Err:adding dept:Editing
Added Dept:Advertising

PL/SQL procedure successfully completed.

上述示例，会成功2条记录；因为在存储过程add_deptartment_a中，当有异常发生的时候，会在自己内部进行处理，外部调用它的函数会认为调用成功；即使此时调用它的外部存储过程create_dept_a存在事务处理机制，也不会发生回滚；再看下面的改造存储过程，就会发生事务回滚处理操作，因为取消了add_department_a中的异常处理；

CREATE OR REPLACE PROCEDURE add_department_a
(
        p_name  VARCHAR2,
        p_mgr   NUMBER,
        p_loc   NUMBER
)
IS
BEGIN
        INSERT INTO DEPARTMENTS(department_id,department_name,manager_id,location_id)
        VALUES(DEPARTMENTS_SEQ.NEXTVAL,p_name,p_mgr,p_loc);

        DBMS_OUTPUT.PUT_LINE('Added Dept:' || p_name);

--EXCEPTION
--      WHEN OTHERS THEN
--              DBMS_OUTPUT.PUT_LINE('Err:adding dept:' || p_name);
END;

/

CREATE OR REPLACE PROCEDURE create_dept_a
IS
BEGIN
        add_department_a('Media_01',100,1800);
        add_department_a('Editing_01',99,1800);
        add_department_a('Advertising_01',101,1800);
EXCEPTION
        WHEN OTHERS THEN
                ROLLBACK;
                DBMS_OUTPUT.PUT_LINE('Err:adding dept!');
END;
/