Stored Procedure and Security Question

Looking for suggestions on the following: A 4gl program that is executable by 3 users, joe, tom, and sue (and many more to come). This 4gl program calls a stored procedure to insert or update a row of data in the "secondary" database. This "secondary" database has all permissions on all tables set to "revoke all" from public. So, joe, tom, sue and other users have no table level permission on secondary, only connect. Only one user, "admin" has complete access and ownership on the "secondary database. This procedure should accept variables : action char(1) "I" or "U", user_id char(8) Unix username, table_name char(17) table name, dml_stat char(200) "where clause, etc". Doing it this way, you need to build your SQL statement with the variables then run it against the database. Any unique ideas on this would be appriciated.... Thanks