Looking at source code of AbstractStatement.java, when the method
"executeQuery" is called, it run the line 166 ("return getResultSet();")
to return the ResultSet object.

Then, if I don't get the ResultSet like this "rs =
stmt.executeQuery(...);", and try to call "getResultSet();" after in the
code, the lines 537-539 arises an exception:
if (currentRs != null) {
throw new FBSQLException("Only one resultset at a time/statement.");
}

Then, I think this is a bug in Jaybird driver, that don't allow
separated calls to "getResultSet();".