JSP 发表新主题总报错！

create sequence seq_article increment by 1 start with 1;create table article(id int primary key not null,pid int,rootid int,title varchar2(255),cont varchar2(4000),pdate date,isleaf int);insert into article (id,pid,rootid,title,cont,pdate,isleaf) values(seq_article.nextval, 0,1,'你好','大家好',sysdate,1);

<%@page pageEncoding="UTF-8"%><%@page import="java.sql.*,bbs.*"%><%    request.setCharacterEncoding("UTF-8");    String action = request.getParameter("action");    if (action != null && action.trim().equals("post")) {        String title = request.getParameter("title");        //System.out.println(title);        String cont = request.getParameter("cont");        //System.out.println(cont);        Connection conn = DB.getConn();        boolean autoCommit = conn.getAutoCommit();        conn.setAutoCommit(false);                String sql = "insert into article values(seq_article.nextval,?,?,?,?,sysdate,?)";        PreparedStatement pstmt = DB.prepareStmt(conn, sql,Statement.RETURN_GENERATED_KEYS);        pstmt.setInt(1, 0);        pstmt.setInt(2, 1);        pstmt.setString(3, title);        pstmt.setString(4, cont);        pstmt.setInt(5, 0);        pstmt.executeUpdate();                ResultSet rsKey = pstmt.getGeneratedKeys();            rsKey.next();                int rootId= rsKey.getInt(1);        Statement stmt = DB.createStmt(conn);        stmt.executeUpdate("update article set rootid=" + rootId + " where id="+ rootId);        conn.commit();        conn.setAutoCommit(autoCommit);        DB.close(stmt);        DB.close(pstmt);        DB.close(conn);        response.sendRedirect("article.jsp");    }%>