Forms :: ORA-01461 When Updating A LONG-Column Via Trigger

I have a non-base-table item which I want to update in the pre-update trigger of the current block.

If the content of the field exceeds 4000 characters, i get the error message

ORA-01461: can bind a LONG value only for insert into a LONG column.

The code is

update tab set long_col = :formsblock.long_col
where tab.tabpk = :formsblock.foreign_tabpk;

Workarounds would be,
1.) to delete the old dataset and insert the new one:

delete from tab
where tab.tabpk = :formsblock.tabpk;

insert into tab (tabpk, long_col) values
(:formsblock.foreign_tabpk, :formsblock.long_col);

or 2.) to change the Item from a non-database item to a database item and use the internal update of the forms-module, but both workarounds are not very satisfying.

Do you know another way to update the LONG-column within the pre-update trigger (or any other PL/SQL part of forms)?