title: Trigger do not see other schema even though it exists
body: <p>I am trying to create trigger so that when we are logging in as application users we don't need to specify the schema prefix for tables. But I am struggling with the error. The trigger looks like this:</p>
  
  <pre><code>CREATE OR REPLACE TRIGGER db_schema.db_logon_app
  AFTER LOGON ON app_schema.schema
  BEGIN
    EXECUTE IMMEDIATE 'ALTER SESSION SET current_schema = DB_SCHEMA';
  END;
  </code></pre>
  
  <p>When I try to execute it the following error appears:</p>
  
  <blockquote>
    <p>Error report:
    ORA-00942: table or view does not exist
    00942. 00000 -  "table or view does not exist"
    *Cause:<br>
    *Action:</p>
  </blockquote>
  
  <p>How to deal with it? Both of the schemas exists and the <code>DB_SCHEMA</code> has <code>ALTER SESSION</code> privilege.</p>
  
  <p>When I am trying to create such trigger just to check that it works everything is fine:</p>
  
  <pre><code>CREATE OR REPLACE TRIGGER db_schema.db_logon_app
  AFTER LOGON ON db_schema.schema
  BEGIN
    EXECUTE IMMEDIATE 'ALTER SESSION SET current_schema = DB_SCHEMA';
  END;
  </code></pre>