解决Hsqldb指针只能单向移动，不能回滚问题（.first()）

Class.forName("org.hsqldb.jdbcDriver").newInstance();
Connection con = java.sql.DriverManager.getConnection("jdbc:hsqldb:hsql://localhost:9001/hadoop", "sa", "");
Statement stmt1 = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);