Oracle APEX – Problem Using Sample Schemas by Oracle

Metalink 207303.1 is the Client/ Server Interoperability Matrix which will be the definitive documentation. Since the express edition of 10g is based on Oracle 10.2, a database link to an 8.1.7 database should be supported. Database links to earlier versions of 8i (8.1.5 or 8.1.6) are not supported from a 10.2 database. For general sanity, I'd strongly suggest that the 8i side be running at least the 8.1.7.4 patchset but that isn't strictly required.

You could encapsulate the logic into the packages themselves:

SQL> CREATE OR REPLACE PACKAGE pkg IS
  2     g_context VARCHAR2(30);
  3     FUNCTION  get_ctx(p_variable VARCHAR2) RETURN VARCHAR2;
  4     -- set_ctx may be private of course
  5     PROCEDURE set_ctx(p_variable VARCHAR2, p_value VARCHAR2);
  6  END;
  7  /

Package created

SQL> CREATE OR REPLACE PACKAGE BODY pkg IS
  2  
  3     FUNCTION  get_ctx(p_variable VARCHAR2) RETURN VARCHAR2 IS
  4     BEGIN
  5        RETURN sys_context(g_context, p_variable);
  6     END get_ctx;
  7  
  8     PROCEDURE set_ctx(p_variable VARCHAR2, p_value VARCHAR2) IS
  9     BEGIN
 10        dbms_session.set_context(g_context, p_variable, p_value);
 11     END set_ctx;
 12  
 13  -- set ctx dynamically
 14  BEGIN
 15     g_context := 'MYCTX_'||sys_context('userenv', 'current_schema');
 16  END;
 17  /

Package body created

Let's create the context and call it :

SQL> BEGIN
  2     EXECUTE IMMEDIATE 'CREATE CONTEXT ' || pkg.g_context || ' USING PKG';
  3  END;
  4  /

PL/SQL procedure successfully completed

SQL> exec pkg.set_ctx ('a', '123');

PL/SQL procedure successfully completed

SQL> select pkg.get_ctx('a') from dual;

PKG.GET_CTX('A')
--------------------------------------------------------------------------------
123