修改資料時用到update語句，使用這個語句時也要有條件的，指定修改某一行的資料，沒有條件判斷，則修改全部。

package qddx.JDBC;
import java.sql.*;
public class UpdatebbsVo {

    public void update(bbsVo vo){
        Connection conn = null;
        PreparedStatement pst = null;
        String sql = "update article set id=?,pid=?,rootid=?, title=?,cont=?,pdate=?,isleaf=? where id=?"
 
;
        try{
        conn = JDBC_Connection.getConnection();
        pst = conn.prepareStatement(sql);
        pst.setInt(1, vo.getId());
        pst.setInt(2, vo.getPid());
        pst.setInt(3, vo.getRootid());
        pst.setString(4, vo.getTitle());
        pst.setString(5, vo.getCont());
        pst.setTimestamp
 
(6, vo.getPdate());
        pst.setInt(7, vo.getIsleaf());
        pst.setInt(8, vo.getId());
        pst.executeUpdate();

        }catch(SQLException e){
            e.printStackTrace();
        }finally{
            JDBC_Connection.free(null, conn, pst);
        }
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        UpdatebbsVo updatebbs = new UpdatebbsVo();
 

        int id = 13;
        int pid = 1;
        int rootid = 1;
        String title = "螞蟻也不好過";
        String cont = "螞蟻也不好過";
        java.util.Date date = new java.util.Date();
        Timestamp pdate = new Timestamp(date.getTime());
        int isleaf = 0;
        QueryById query = new QueryById();
        bbsVo bvo = new bbsVo();
        bvo = query.QuerybbsVoById(id);
        if(bvo!=null){
            bbsVo vo = new bbsVo();
            vo.setId(id);
            vo.setPid(pid);
            vo.setRootid(rootid);
            vo.setTitle(title);
            vo.setCont(cont);
            vo.setPdate(pdate);
            vo.setIsleaf(isleaf);
            updatebbs.update(vo);
            System.out.println("修改了 id為 "+id+"的資料");
        }else{
            System.out.println("id 為 "+id+" 的資料不存在");
        }
    }

}