> You can't concatenate strings to blobs or blobs to blobs.
>
> There are external functions (see FreeUDFLib) that can convert a blob to a
> string, that you could try out in a stored procedure. You would have to
> recreate the blob inside the SP, since blobs are never updated, always
> replaced with a completely new blob and new blob_id.
>
> The trap here is that varchars have a length limit of 32765 bytes, whereas
> blobs have no length limit.

It is trivial to write UDF that concatenates blob and string or two blobs,
so char/varchar length limit is no issue here.

Ivan