Private Constructs in Packages

Question

Can't I refer a private function in a SQL statement which is inside a Public Procedure. Both Private Function and Public Procedure are in the same Package.
I just recreated the scenario using a simple procedure and a function inside a Package. Please take a look at the errors which I got when trying to create the package body.
CREATE OR REPLACE PACKAGE Pac_1 AS
PROCEDURE Pub_Pro;
END pac_1;
CREATE OR REPLACE PACKAGE BODY Pac_1 AS
FUNCTION Pri_Fun RETURN VARCHAR2 AS
BEGIN
RETURN 'Vamsi';
END Pri_Fun;
PROCEDURE Pub_Pro AS
BEGIN
INSERT INTO Test VALUES (Pri_Fun);
END Pub_Pro;
END Pac_1;
ERROR I GOT
Line Pos Text
116 Create package body, executed in 0.107 sec.
130 26 PLS-00231: function 'PRI_FUN' may not be used in SQL
130 26 PL/SQL: ORA-00904: "PRI_FUN": invalid identifier
130 1 PL/SQL: SQL Statement ignored
Total execution time 0.122 sec.
* Same execution works if the make the Function I used as a Public Function by also declaring it in the Package Specification AND also works if I use the function in a PL/SQL expression and not in a SQL statement.*
Thanks in Advance.
Vamsi

Answer 1

This is absolutely natural behaviour.
Look at in what Oracle translates your call of the SQL statement from PL/SQL then the function
is specified as public:
SQL> CREATE OR REPLACE PACKAGE Pac_1 AS
  2 
  3   PROCEDURE Pub_Pro;
  4   FUNCTION Pri_Fun RETURN VARCHAR2;
  5 
  6  END pac_1;
  7  /
Package created.
SQL> CREATE OR REPLACE PACKAGE BODY Pac_1 AS
  2 
  3 
  4   FUNCTION Pri_Fun RETURN VARCHAR2 AS
  5 
  6    BEGIN
  7 
  8    RETURN 'Vamsi';
  9 
10   END Pri_Fun;
11 
12 
13   PROCEDURE Pub_Pro AS
14 
15   BEGIN
16 
17    INSERT INTO Test easy_to_find VALUES (Pri_Fun);
18 
19   END Pub_Pro;
20 
21  END Pac_1;
22  /
Package body created.
SQL> exec pac_1.pub_pro
PL/SQL procedure successfully completed.
SQL> select sql_text from v$sqlarea where sql_text like '%EASY_TO_FIND%';
SQL_TEXT
INSERT INTO TEST EASY_TO_FIND VALUES (PAC_1.PRI_FUN)The last row is the real form of INSERT operator. It shows that Oracle resolves this reference by
trying to use the public function from the package specification.
If you want to use private function in SQL you have to use local variables:
SQL> CREATE OR REPLACE PACKAGE Pac_1 AS
  2 
  3   PROCEDURE Pub_Pro;
  4 
  5  END pac_1;
  6  /
Package created.
SQL> CREATE OR REPLACE PACKAGE BODY Pac_1 AS
  2 
  3 
  4   FUNCTION Pri_Fun RETURN VARCHAR2 AS
  5    BEGIN
  6    RETURN 'Vamsi';
  7   END Pri_Fun;
  8 
  9 
10   PROCEDURE Pub_Pro AS
11    x varchar2(10);
12   BEGIN
13    x := pri_fun;
14    INSERT INTO Test easy_to_find VALUES (x);
15   END Pub_Pro;
16 
17  END Pac_1;
18  /
Package body created.And meanwhile it would be better to use local variable form even if your function is public ;)
Rgds.