@UNQKVB[[u,]filename,"key",bhandle,length] : Add a key / binary blob value pair to a UnQLite database.
|u||Optional flag that the key and value are Unicode (UTF16)|
|filename||Database opened with @UNQOPEN|
|key||Key to add or replace|
|bhandle||Binary handle returned by @BALLOC|
|length||Length of binary buffer to write (or -1 for the entire buffer)|
Returns 0 if successful, or the error text if not.
This example opens a database named "test.db", then allocates a binary buffer, writes it to the database, and then reads it back.