Can JoinFieldValue function be used for custom objects 4 and 5? If I want to update the Account field on custom object 5 based on the Account field in custom object 4, can this be done using JoinFieldValue ? How?
Currently JoinFieldValue is not supported in Custom Objects 04-15. You will have to use web services for Updating Account field on Custom Object 5 or else you can try the URL method to update the Account field .