《（学习笔记）两天进步一点点》（2） ——BindingSource基础操作

以前在进行数据绑定的时候，通常用的数据源有DataSet、DataTable、BindingList<T>、还有强类型数据源。今天呢、我看了一下BindingSource组建，感觉还不错特将学习笔记分大家分享。

一、BindingSource的两个用途

（1）首先，它提供一个将窗体上的控件绑定到数据的间接层。这是通过将 BindingSource 组件绑定到数据源，然后将窗体上的控件绑定到 BindingSource 组件来完成的。与数据的所有进一步交互（包括导航、排序、筛选和更新）都是通过调用 BindingSource 组件来完成的。

（2）其次，BindingSource 组件可以充当强类型数据源。使用 Add 方法向 BindingSource 组件添加类型会创建一个该类型的列表。

一、对BindingSource的基础操作——增删改查

绑定 DBNull 值

//***********************************************************************
下面的示例演示如何在两种不同情况下绑定 DBNull 值。第一种情况演示如何设置字符串属性的 NullValue；第二种情况演示如何设置图像属性的 NullValue。
//***********************************************************************

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Data.SqlClient;
using System.Windows.Forms;

namespace DBNullCS
{
public class Form1 : Form
{
public Form1()
{
this.Load += new EventHandler(Form1_Load);
}

// The controls and components we need for the form.
private Button button1;
private PictureBox pictureBox1;
private BindingSource bindingSource1;
private TextBox textBox1;
private TextBox textBox2;

// Data table to hold the database data.
DataTable employeeTable = new DataTable();

void Form1_Load(object sender, EventArgs e)
{
// Basic form setup.
this.pictureBox1 = new PictureBox();
this.bindingSource1 = new BindingSource();
this.textBox1 = new TextBox();
this.textBox2 = new TextBox();
this.button1 = new Button();
this.pictureBox1.Location = new System.Drawing.Point(20, 20);
this.pictureBox1.Size = new System.Drawing.Size(174, 179);
this.textBox1.Location = new System.Drawing.Point(25, 215);
this.textBox1.ReadOnly = true;
this.textBox2.Location = new System.Drawing.Point(25, 241);
this.textBox2.ReadOnly = true;
this.button1.Location = new System.Drawing.Point(200, 103);
this.button1.Text = "Move Next";
this.button1.Click += new System.EventHandler(this.button1_Click);
this.ClientSize = new System.Drawing.Size(292, 273);
this.Controls.Add(this.button1);
this.Controls.Add(this.textBox2);
this.Controls.Add(this.textBox1);
this.Controls.Add(this.pictureBox1);
this.ResumeLayout(false);
this.PerformLayout();

// Create the connection string and populate the data table
// with data.
string connectionString = "Integrated Security=SSPI;" +
"Persist Security Info = False;Initial Catalog=Northwind;" +
"Data Source = localhost";
SqlConnection connection = new SqlConnection();
connection.ConnectionString = connectionString;
SqlDataAdapter employeeAdapter =
new SqlDataAdapter(new SqlCommand("Select * from Employees", connection));
connection.Open();
employeeAdapter.Fill(employeeTable);

// Set the DataSource property of the BindingSource to the employee table.
bindingSource1.DataSource = employeeTable;

// Set up the binding to the ReportsTo column.
Binding reportsToBinding = textBox2.DataBindings.Add("Text", bindingSource1,
"ReportsTo", true);

// Set the NullValue property for this binding.
reportsToBinding.NullValue = "No Manager";

// Set up the binding for the PictureBox using the Add method, setting
// the null value in method call.
pictureBox1.DataBindings.Add("Image", bindingSource1, "Photo", true,
DataSourceUpdateMode.Never, new Bitmap(typeof(Button), "Button.bmp"));

// Set up the remaining binding.
textBox1.DataBindings.Add("Text", bindingSource1, "LastName", true);
}

// Move through the data when the button is clicked.
private void button1_Click(object sender, EventArgs e)
{
bindingSource1.MoveNext();
}

[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.Run(new Form1());
}

}
}

《（学习笔记）两天进步一点点》持续更新中…　　望大侠们指点一二，谢谢！