I've has found the problem:
If the view is created for the table with blobs sub_type 0 , and the view has
CHECK OPTION, it's impossible to modify the record regardless to the column
type. The Interbase tries by itself to compare old and new values of blobs and
reports, that this feature is not supported.
If the view doesn't have check option, all is OK.
Manualy creation triggers for the view which raise the exception allows to pass
this problem.
So as I think the problem is that Interbase checks not only the field in WHERE
clause.


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With respect
Alexander Rabtchevich