Select with 21 fields always return empty resultset without any errors

[bat22]

Select with 21 fields always return empty result without any errors. Example: https://gist.github.com/bat22/5960fda6aa8a02d6a6284bf7e07237a9

[nakagami]

Thanks a lot !

I have found this code is a bit different from pyfirebirdsql https://github.com/nakagami/pyfirebirdsql/blob/master/firebirdsql/xsqlvar.py#L303 . And modify like pyfirebirdsql.

But your PR and example code was very helpful.