包头(Package)与包体(Package body)的应用

包头(Package)与包体(Package body)的应用

1.将有联系的对象打成包,方便使用
2.包中对象包括储存过程,函数,游标,自定义类型和变量,可以在PL_SQL块中应用这些对象.

定义包头:
----------------------------------------------------------------------------------------------
create or replace package is
  type is ;--定义类型
  -- Public constant declarations
  constant := ;--声明常量
  -- Public variable declarations
  ;  --数据类型
  -- Public function and procedure declarations
  function ( ) return ; --函数
end ;

定义包体:
----------------------------------------------------------------------------------------------
create or replace package body is
  -- Private type declarations
  type is ;
  -- Private constant declarations
  constant :=
  -- Private variable declarations
  ;
  -- Function and procedure implementations
  function ( ) return is --函数的具体内容
    ;
  begin
    ;
    return();
  end;
begin
  -- Initialization--初始化包体,每次调用时被初始化
  ;
end ;

只有当包头编辑成功后才能编辑包体.其中的函数名与过程名须和包头中的函数过程一样.

学习包应用的一个例子: 
包的作用: 根据出生年月返回年龄function Getage,返回工资function Getsalary
--创建环境
Create Table T_PsnSalary  --工资表
(
Fpsncode varchar(4) default '',  --个人代码
Fpsndesc varchar(20) default '',  --描述
FpsnBirth varchar(20) default '', --生日
FpsnSalary number(8,2)            --工资
);

--添加数据
Insert into T_PsnSalary(Fpsncode,Fpsndesc,FpsnBirth,FpsnSalary) Values('C001','张三','1986.01.10',1100);
Insert into T_PsnSalary(Fpsncode,Fpsndesc,FpsnBirth,FpsnSalary) Values('C002','李四','1980.10.10',3000);
Insert into T_PsnSalary(Fpsncode,Fpsndesc,FpsnBirth,FpsnSalary) Values('C003','王五','1996.12.10',800);
commit;

--创建包头
create or replace package A_GetData is
  function Getage(birthst varchar,birthend varchar) return integer;
  function Getsalary(VFpsncode varchar) return number;
end A_Getdata;

--创建包体
create or replace package body A_GETDATA is
  function Getage(birthst varchar,birthend varchar) return integer --得到年龄函数
  is
     V_birth integer;
     ToDateEnd Date;
     Toyear number(4);
     Tomonth number(4);
     Fromyear number(4);
     Frommonth number(4);
  begin
    if (birthend='') or (birthend is null) then
    select sysdate into ToDateEnd from dual; --得到系统时间
    end if;
    Toyear := to_number(to_char(ToDateEnd,'YYYY')); --得到最后年月
    Tomonth := to_number(to_char(ToDateEnd,'MM'));
    Fromyear := to_number(substr(birthst,1,4));--计算的年月
    Frommonth := to_number(substr(birthst,6,2));
    if Tomonth-Frommonth>0 then V_birth:=Toyear-fromyear;
    else V_birth:=Toyear-fromyear-1;
    end if;
    return(V_birth);
  end Getage;

  function getSalary(VFpsncode varchar) return number--返回工资情况
  is
    V_psnSalary number(8,2);
  begin
    Select FpsnSalary into V_psnSalary from T_PsnSalary  where Fpsncode=VFpsncode;
    return(V_psnSalary);
  end getSalary;
 
end A_GETDATA;

--测试
select a.*,A_getdata.Getage(Fpsnbirth,'')age from T_psnsalary a;  --调用包得到年龄功能
select A_getdata.Getsalary('C001') from dual;                     --代码得到工资