包
练习 1:
--创建package header
CREATE OR REPLACE PACKAGE emp_pack
IS
PROCEDURE new_emp
(v_ename emp.ename%TYPE,
v_job emp.job%TYPE DEFAULT 'SALESMAN',
v_mgr emp.mgr%TYPE DEFAULT 7839,
v_sal emp.sal%TYPE DEFAULT 1000,
v_comm emp.comm%TYPE DEFAULT 0,
v_deptno emp.deptno%TYPE DEFAULT 30);
END emp_pack;
/
--创建package body
CREATE OR REPLACE PACKAGE BODY emp_pack
IS
FUNCTION valid_deptno --私有函数
(v_deptno IN dept.deptno%TYPE)
RETURN BOOLEAN
IS
v_dummy VARCHAR2(1);
BEGIN
SELECT 'x'
INTO v_dummy
FROM dept
WHERE deptno = v_deptno;
RETURN (TRUE);
EXCEPTION
WHEN NO_DATA_FOUND THEN
RETURN(FALSE);
END valid_deptno;
PROCEDURE new_emp
(v_ename emp.ename%TYPE,
v_job emp.job%TYPE DEFAULT 'SALESMAN',
v_mgr emp.mgr%TYPE DEFAULT 7839,
v_sal emp.sal%TYPE DEFAULT 1000,
v_comm emp.comm%TYPE DEFAULT 0,
v_deptno emp.deptno%TYPE DEFAULT 30)
IS
BEGIN
IF valid_deptno(v_deptno) THEN
INSERT INTO emp
VALUES (seq_empno.NEXTVAL, v_ename, v_job, v_mgr,
TRUNC (SYSDATE, 'DD'), v_sal, v_comm, v_deptno);
ELSE
DBMS_OUTPUT.PUT_LINE('Invalid department number. Try again.');
END IF;
END new_emp;
END emp_pack;
/
为PACKAGE BODY加密:
wrap iname=1.sql
sql>@1.plb
----------------------------------------------------------------------
练习 2:重载
--创建package header
CREATE OR REPLACE PACKAGE over_load is
FUNCTION print_it(v_arg date)
RETURN VARCHAR2;
FUNCTION print_it(v_arg VARCHAR2)
RETURN VARCHAR2;
END over_load;
/
--创建package body
CREATE OR REPLACE PACKAGE BODY over_load is
FUNCTION print_it(v_arg date)
RETURN VARCHAR2
IS
BEGIN
RETURN to_char(v_arg,'yyyy-mm-dd');
END print_it;
FUNCTION print_it(v_arg VARCHAR2)
RETURN VARCHAR2
IS
BEGIN
RETURN to_char(v_arg,'L99,999.00');
END print_it;
END over_load;
/
--包的调用
VARIABLE g_datevalue varchar2(40);
execute :g_datevalue := over_load.PRINT_IT(sysdate);
print g_datevalue
VARIABLE g_datevalue varchar2(40);
execute :g_datevalue := over_load.PRINT_IT('123');
print g_datevalue
----------------------------------------------------------------------
包与依赖:断开了依赖链
DROP TABLE T;
create table t (x int);
create view v as select * from t;
create procedure p
is
begin
for x in (select * from v)
loop
null;
end loop;
end;
/
create function f return number
is
l_cnt number;
begin
select count(*) into l_cnt from t;
return l_cnt;
end;
/
查看依赖关系：
select name,type,referenced_name,referenced_type
from user_DEPENDENCIES
where name IN ('F','P','T','V')
AND referenced_owner='SCOTT'
order by name;
查看对象有效状态：
select object_name,object_type,status
from user_objects
where object_name in ('F','P','T','V');
修改T表结构后，再看有效性：
alter table t add y number;
select object_name,object_type,status
from user_objects
where object_name in ('F','P','T','V');
V P F 无效
创建一个依赖P的过程后，再看有效性：
create procedure p2
is
begin
p;
end;
/
select object_name,object_type,status
from user_objects
where object_name in ('F','P','P2','T','V');
V P 重新有效！对P2的编译同时重新编译了V P！
使用包重做上面的实验：
create package pk1
is
procedure p;
end;
/
create package body pk1
is
procedure p
is
begin
for x in (select * from v)
loop
null;
end loop;
end;
end pk1;
/
create package pk2
is
procedure p;
end;
/
create package body pk2
is
procedure p
is
begin
pk1.p;
end;
end pk2;
/
select object_name,object_type,status
from user_objects
where object_name in ('F','P','P2','T','V','PK1','PK2');
再次修改T，再查看有效性！PK1 包体无效了！因为PK1 包体通过V依赖与T（依赖链）
而PK2仍然有效！PK2依赖与PK1而不是PK1包体（因而断开了依赖链）！
exec pk2.p;
select object_name,object_type,status
from user_objects
where object_name in ('F','P','P2','T','V','PK1','PK2');
