问题
I have created a function which return NUMBER type in a package, but not declare this function in the Package Specification.
I am calling this function in SQL query in anther function with in same package body. I am getting error.
When i declare function in Package Specification Then its fine & working.
I want to know reason behind it. Please anybody explain it.
回答1:
Nothing to do with forward declaration at all.
This deals with the fact that you are using a SQL query to call the function. It seems like when using a statement to invoke a function, you are no longer inside the scope of the PL/SQL package, thus you can only call publicly available functions.
As for the why, I can only guess, so don't take it as granted, but PL/SQL and SQL have different engines. So, when doing a sql query, even inside your pl/sql package, you go to the level of SQL where it'll check again the permissions according to the SQL engine. So it has no idea it is executed from within a PL/SQL package and you should be allowed to call the private function.
I think the difference of engines can be checked easily, try to use a varchar2 of 32000, it'll work within your pl/sql function. Now, if you call your pl/sql function returning a varchar2(32000), it'll fail. Thi is a problem I ran into, but I don't have any databse to give you a snippet.
回答2:
You can use functions that are declared only in the package body, but you have to declare them before they are first used:
create or replace package pkg_so is
function get2 return number;
end pkg_so;
/
create or replace package body pkg_so is
function get1 return number is
begin
return 1;
end;
function get2 return number is
begin
return get1 + 1;
end;
end pkg_so;
/
select pkg_so.get2 from dual
/
回答3:
yeah this is called forward declaration.If any procedure/function is not declare in package sepcificarion. Then it must be first declare in body before the first used in body.
create or replace package pkg_so is
function get2 return number;
end pkg_so;
/
create or replace package body pkg_so is
function get1 return number is
begin
return 1;
end;
function get2 return number is
begin
return get1 + 1;
end;
end pkg_so;
/
select pkg_so.get2 from dual
/
来源：https://stackoverflow.com/questions/14725559/getting-error-when-calling-any-function-in-sql-query-in-a-package-without-declar