看这个数据绑定的问题？

Question

你可以直接使用TEXTBOX的DataBoundings来加入数据源的

Answer 1

选中TextBox,在属性窗口的最上方有个"(DataBinding)",选中它，右边会出现一个按钮，点击这个按钮你就会明白了！！

Answer 2

下面是我全部源代码，现在textBox中可以显示一条记录了，但当我点击“下一条”按钮时，报错，没将对象引用到实例，我该如何解决？
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Data.OleDb;namespace WindowsApplication1
{
/// <summary>
/// Form1 的摘要说明。
/// </summary>
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.Button button1;
private System.Windows.Forms.Button button2;
private System.Windows.Forms.Button button3;
private System.Windows.Forms.Button button4;
private System.Windows.Forms.TextBox textBox2;

private System.Data.DataSet dataSet1;
private BindingManagerBase myBind;
private System.Windows.Forms.TextBox textBox3;
private System.ComponentModel.Container components=null;
public Form1()
{
//
// Windows 窗体设计器支持所必需的

//
InitializeComponent();
GetConnect();
//
// TODO: 在 InitializeComponent 调用后添加任何构造函数代码
//
} /// <summary>
/// 清理所有正在使用的资源。
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null) 
{
components.Dispose();
}
}
base.Dispose( disposing );
} #region Windows Form Designer generated code
/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.button1 = new System.Windows.Forms.Button();
this.button2 = new System.Windows.Forms.Button();
this.button3 = new System.Windows.Forms.Button();
this.button4 = new System.Windows.Forms.Button();
this.textBox2 = new System.Windows.Forms.TextBox();
this.textBox3 = new System.Windows.Forms.TextBox();
this.SuspendLayout();
// 
// textBox1
// 
this.textBox1.Location = new System.Drawing.Point(80, 48);
this.textBox1.Name = "textBox1";
this.textBox1.TabIndex = 0;
this.textBox1.Text = "textBox1";
// 
// button1
// 
this.button1.Location = new System.Drawing.Point(16, 152);
this.button1.Name = "button1";
this.button1.TabIndex = 1;
this.button1.Text = "button1";
this.button1.Click += new System.EventHandler(this.button1_Click);
// 
// button2
// 
this.button2.Location = new System.Drawing.Point(96, 152);
this.button2.Name = "button2";
this.button2.TabIndex = 2;
this.button2.Text = "button2";
this.button2.Click += new System.EventHandler(this.button2_Click);
// 
// button3
// 
this.button3.Location = new System.Drawing.Point(176, 152);
this.button3.Name = "button3";
this.button3.TabIndex = 3;
this.button3.Text = "button3";
this.button3.Click += new System.EventHandler(this.button3_Click);
// 
// button4
// 
this.button4.Location = new System.Drawing.Point(256, 152);
this.button4.Name = "button4";
this.button4.TabIndex = 4;
this.button4.Text = "button4";
this.button4.Click += new System.EventHandler(this.button4_Click);
// 
// textBox2
// 
this.textBox2.Location = new System.Drawing.Point(80, 80);
this.textBox2.Name = "textBox2";
this.textBox2.TabIndex = 5;
this.textBox2.Text = "textBox2";
// 
// textBox3
// 
this.textBox3.Location = new System.Drawing.Point(80, 112);
this.textBox3.Name = "textBox3";
this.textBox3.TabIndex = 6;
this.textBox3.Text = "textBox3";
// 
// Form1
// 
this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
this.ClientSize = new System.Drawing.Size(392, 293);
this.Controls.AddRange(new System.Windows.Forms.Control[] {
  this.textBox3,
  this.textBox2,
  this.button4,
  this.button3,
  this.button2,
  this.button1,
  this.textBox1});
this.Name = "Form1";
this.Text = "Form1";
this.Load += new System.EventHandler(this.Form1_Load);
this.ResumeLayout(false); }
#endregion /// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
public void GetConnect()
{
try
{
string strconn="Provider = Microsoft.Jet.OLEDB.4.0 ; Data Source = access.mdb" ;
OleDbConnection myole= new OleDbConnection(strconn);
string strcom="select * from con";
dataSet1=new DataSet();
myole.Open(); OleDbDataAdapter oda=new OleDbDataAdapter(strcom,myole);
oda.Fill(dataSet1,"con");
textBox1.DataBindings.Add("Text",dataSet1,"con.id");
textBox2.DataBindings.Add("Text",dataSet1,"con.content");
textBox3.DataBindings.Add("Text",dataSet1,"con.memo");
myole.Close();
}
catch(Exception exp)
{
MessageBox.Show(exp.ToString(),"错误");
}
}
static void Main() 
{
Application.Run(new Form1());
} private void Form1_Load(object sender, System.EventArgs e)
{

} private void timer1_Tick(object sender, System.EventArgs e)
{

} private void button1_Click(object sender, System.EventArgs e)
{
myBind.Position=0;
} private void button2_Click(object sender, System.EventArgs e)
{
if(myBind.Position==0)
MessageBox.Show("已到了第一条记录！");
else
myBind.Position-=1;
} private void button3_Click(object sender, System.EventArgs e)
{
if(myBind.Position==myBind.Count-1)
MessageBox.Show("已到了最后一条！");
else 
myBind.Position+=1;
} private void button4_Click(object sender, System.EventArgs e)
{
myBind.Position=myBind.Count-1;
}
}
}

Answer 3

在myole.Close();前面给myBind 赋值就可以了.
myBind = this.BindingContext[dataSet1, "con"];
完整代码如下:
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Data.OleDb;namespace WindowsApplication1
{
/// <summary>
/// Form1 的摘要说明。
/// </summary>
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.Button button1;
private System.Windows.Forms.Button button2;
private System.Windows.Forms.Button button3;
private System.Windows.Forms.Button button4;
private System.Windows.Forms.TextBox textBox2; private System.Data.DataSet dataSet1;
private BindingManagerBase myBind;
private System.Windows.Forms.TextBox textBox3;
private System.ComponentModel.Container components=null;
public Form1()
{
//
// Windows 窗体设计器支持所必需的 //
InitializeComponent();
GetConnect();
//
// TODO: 在 InitializeComponent 调用后添加任何构造函数代码
//
} /// <summary>
/// 清理所有正在使用的资源。
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}#region Windows Form Designer generated code
/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.button1 = new System.Windows.Forms.Button();
this.button2 = new System.Windows.Forms.Button();
this.button3 = new System.Windows.Forms.Button();
this.button4 = new System.Windows.Forms.Button();
this.textBox2 = new System.Windows.Forms.TextBox();
this.textBox3 = new System.Windows.Forms.TextBox();
this.SuspendLayout();
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(80, 48);
this.textBox1.Name = "textBox1";
this.textBox1.TabIndex = 0;
this.textBox1.Text = "textBox1";
//
// button1
//
this.button1.Location = new System.Drawing.Point(16, 152);
this.button1.Name = "button1";
this.button1.TabIndex = 1;
this.button1.Text = "button1";
this.button1.Click += new System.EventHandler(this.button1_Click);
//
// button2
//
this.button2.Location = new System.Drawing.Point(96, 152);
this.button2.Name = "button2";
this.button2.TabIndex = 2;
this.button2.Text = "button2";
this.button2.Click += new System.EventHandler(this.button2_Click);
//
// button3
//
this.button3.Location = new System.Drawing.Point(176, 152);
this.button3.Name = "button3";
this.button3.TabIndex = 3;
this.button3.Text = "button3";
this.button3.Click += new System.EventHandler(this.button3_Click);
//
// button4
//
this.button4.Location = new System.Drawing.Point(256, 152);
this.button4.Name = "button4";
this.button4.TabIndex = 4;
this.button4.Text = "button4";
this.button4.Click += new System.EventHandler(this.button4_Click);
//
// textBox2
//
this.textBox2.Location = new System.Drawing.Point(80, 80);
this.textBox2.Name = "textBox2";
this.textBox2.TabIndex = 5;
this.textBox2.Text = "textBox2";
//
// textBox3
//
this.textBox3.Location = new System.Drawing.Point(80, 112);
this.textBox3.Name = "textBox3";
this.textBox3.TabIndex = 6;
this.textBox3.Text = "textBox3";
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
this.ClientSize = new System.Drawing.Size(392, 293);
this.Controls.AddRange(new System.Windows.Forms.Control[] {
  this.textBox3,
  this.textBox2,
  this.button4,
  this.button3,
  this.button2,
  this.button1,
  this.textBox1});
this.Name = "Form1";
this.Text = "Form1";
this.Load += new System.EventHandler(this.Form1_Load);
this.ResumeLayout(false); }
#endregion /// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
public void GetConnect()
{
try
{
string strconn="Provider = Microsoft.Jet.OLEDB.4.0 ; Data Source = access.mdb" ;
OleDbConnection myole= new OleDbConnection(strconn);
string strcom="select * from con";
dataSet1=new DataSet();
myole.Open(); OleDbDataAdapter oda=new OleDbDataAdapter(strcom,myole);
oda.Fill(dataSet1,"con");
textBox1.DataBindings.Add("Text",dataSet1,"con.id");
textBox2.DataBindings.Add("Text",dataSet1,"con.content");
textBox3.DataBindings.Add("Text",dataSet1,"con.memo");
myBind = this.BindingContext[dataSet1, "con"]; myole.Close();
}
catch(Exception exp)
{
MessageBox.Show(exp.ToString(),"错误");
}
}
static void Main()
{
Application.Run(new Form1());
} private void Form1_Load(object sender, System.EventArgs e)
{ } private void timer1_Tick(object sender, System.EventArgs e)
{ } private void button1_Click(object sender, System.EventArgs e)
{
myBind.Position=0;
} private void button2_Click(object sender, System.EventArgs e)
{
if(myBind.Position==0)
MessageBox.Show("已到了第一条记录！");
else
myBind.Position-=1;
} private void button3_Click(object sender, System.EventArgs e)
{
if(myBind.Position==myBind.Count-1)
MessageBox.Show("已到了最后一条！");
else
myBind.Position+=1;
} private void button4_Click(object sender, System.EventArgs e)
{
myBind.Position=myBind.Count-1;
}
}
}