Consider that there are 2 users in your database having their own schemas, but second user having less permission is required to work on the first schema. Possible solutions :
1 . To create public/private synonyms
2. Use schema name in the queries.
3. Modify user session to point the first schema. Create a trigger on login.
CREATE OR REPLACE TRIGGER &app_user..APP_USER_LOGON AFTER LOGON ON &app_user..SCHEMA DECLARE
BEGIN
EXECUTE IMMEDIATE 'ALTER SESSION SET CURRENT_SCHEMA = '|| UPPER('&owner_user');
EXCEPTION
WHEN OTHERS THEN raise_application_error(-20001, 'Error: ' || SQLERRM );
END ;
