DGV修改保存问题!
											 程序代码:
程序代码:using System;
using System.Collections.Generic;
using using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Configuration;
namespace WindowsFormsApplication2
{
    public partial class Form4 : Form
    {
        protected SqlConnection con;
        protected SqlCommand cmd;
        protected SqlDataAdapter dr;
        protected DataSet ds;
        public Form4()
        {
            InitializeComponent();
        }
        private void Form4_Load(object sender, EventArgs e)
        {
            try
            {
                con = new SqlConnection("server=.;database=BookStore;uid=sa;pwd=saa");
                cmd = new SqlCommand();
                cmd.Connection = con;
                con.Open();
                this.InitData();
            }
            catch (Exception exp)
            {
                MessageBox.Show("数据库无法访问:" + exp.Message);
                this.Close();
            }
            finally
            {
                if (con != null && con.State != ConnectionState.Closed)
                    con.Close();
            }
        }   
        private void Sea_Click(object sender, EventArgs e)
        {
            StringBuilder sb = new StringBuilder();
            if (!chkByName.Checked && !chkByPuslish.Checked && !chkByAuthor.Checked)
            {
                MessageBox.Show("至少输入一个查询条件","温馨提示",MessageBoxButtons.OK,MessageBoxIcon.Warning);
                return;
            }
            if (chkByName.Checked)
            {
                this.byName();
            }
            else if (chkByName.Checked && txtByName.Text == "")
            {
                MessageBox.Show("请输入书名", "温馨提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                txtByName.Focus();
                return;
            }
            if (chkByPuslish.Checked)
            {
                this.bypublish();
            }
            else if (chkByPuslish.Checked && cmbPublish.Text == "")
            {
                MessageBox.Show("请输入出版社名", "温馨提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                cmbPublish.Focus();
                return;
            }
            if (chkByAuthor.Checked)
            {
                this.byAuthor();
            }
            else if (chkByAuthor.Checked && txtAuthor.Text == "")
            {
                MessageBox.Show("请输入作者", "温馨提示", MessageBoxButtons.OK,
                    MessageBoxIcon.Warning);
                txtAuthor.Focus();
                return;
            }
           
        }           //条件查询
        private void Res_Click(object sender, EventArgs e)
        {
            chkByAuthor.Checked = false;
            chkByName.Checked = false;
            chkByPuslish.Checked = false;
            txtAuthor.Text = "";
            txtByName.Text = "";
            cmbPublish.Text = "";
            cmbBookCode.Text = "";
            DataTable dt = (DataTable)dataGridView1.DataSource;
            dt.Rows.Clear();
            dataGridView1.DataSource = dt;
        }           //重置
        private void All_Click(object sender, EventArgs e)
        {
            dr = new SqlDataAdapter("select * from Book", con);
            ds = new DataSet();
            dr.Fill(ds, "Book");
            dataGridView1.DataSource = ds.Tables["Book"];
            try
            {
                if (ds.HasChanges())
                {
                    SqlCommandBuilder cb = new SqlCommandBuilder(dr);
                    dr.Update(ds);
                    dataGridView1.Update();
                    MessageBox.Show("修改成功", "提示");
                }
            }
            catch
            {
                MessageBox.Show("修改失败", "提示");
            }
        }           //所有
        private void btnLocate_Click(object sender, EventArgs e)
        {
            int row = dataGridView1.Rows.Count;//得到总行数
            int cell = dataGridView1.Rows[1].Cells.Count;//得到总列数
            for (int i = 0; i < row; i++)//得到总行数并在之内循环
            {
                for (int j = 0; j < cell; j++)//得到总列数并在之内循环
                {
                    if (cmbBookCode.Text== dataGridView1.Rows[i].Cells[j].Value.ToString())
                    {   //对比TexBox中的值是否与dataGridView中的值相同(上面这句)
                        this.dataGridView1.CurrentCell = this.dataGridView1[j, i];//定位到相同的单元格
                        return;//返回
                    }
                }
            }
 
        }     //快速定位
        private void InitData()
        {
            cmd = new SqlCommand("select distinct Press from Book order by Press", con);
            SqlDataReader reader = cmd.ExecuteReader();
            cmbPublish.Items.Clear();
            while (reader.Read())
            {
                cmbPublish.Items.Add(reader[0]);
            }
            reader.Close();
             = "select distinct Barcode from Book order by Barcode";
            reader = cmd.ExecuteReader();
            cmbBookCode.Items.Clear();
            while (reader.Read())
            {
                cmbBookCode.Items.Add(reader[0]);
            }
            reader.Close();
        }
       
        private void byName()
        {
            ds = new DataSet();
            dr = new SqlDataAdapter("select * from Book where Name like '%"+txtByName.Text+"%'",con);
            dr.Fill(ds, "Book");
            dataGridView1.DataSource = ds.Tables["Book"];
        }//按书名查询
        private void bypublish()
        {
            ds = new DataSet();
            dr = new SqlDataAdapter("select * from Book where Press like '%" + cmbPublish.Text + "%'", con);
            dr.Fill(ds, "Book");
            dataGridView1.DataSource = ds.Tables["Book"];  
        }//按出版社查询
        private void byAuthor()
        {
            ds = new DataSet();
            dr = new SqlDataAdapter("select * from Book where Author like '%" + txtAuthor.Text + "%'", con);
            dr.Fill(ds, "Book");
            dataGridView1.DataSource = ds.Tables["Book"];  
        }//按作者查询
        private void button3_Click(object sender, EventArgs e)
        {
            if (MessageBox.Show("真的要退出系统吗??", "温馨提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information)
               == DialogResult.OK)
            {
                this.Close();
                this.Dispose();
            }
            else
            {
            }
        }
        private void button1_Click(object sender, EventArgs e)
        {
          
        }
    }
}
	
		
			
		
	
我现在在保存修改上难住了。求大大帮忙。。。。。 附上代码...

 
											






 
	    

