参考文章：

1，http://topic.csdn.net/u/20091027/16/b804ebc8-c88c-4c05-9652-d198d4b4f0fb.html

privatevoidForm1_Load(objectsender, EventArgs e)
        {
            SqlConnection con=newSqlConnection(conn);
            con.Open();
            SqlCommand cmd=newSqlCommand("select * from department",con);          
            SqlDataAdapter sda=newSqlDataAdapter(cmd);
            DataTable dt=newDataTable();
            sda.Fill(dt);
            con.Close();
            comboBox1.DataSource=dt;
            comboBox1.DisplayMember="department";
            comboBox1.ValueMember="departmentId";

        }

       privatevoidcomboBox1_SelectedIndexChanged(objectsender, EventArgs e)
        {
           if(comboBox1.SelectedIndex>-1)
            {
                DataRowView drv=(DataRowView)comboBox1.SelectedItem;
               intid=Convert.ToInt32(drv.Row["departmentId"].ToString());
                SqlConnection con=newSqlConnection(conn);
                con.Open();
                SqlCommand cmd=newSqlCommand("select * from major where departmentId='"+id+"'", con);
                SqlDataAdapter sda=newSqlDataAdapter(cmd);            
                DataTable dt=newDataTable();
                sda.Fill(dt);
                comboBox2.DataSource=dt;
                comboBox2.DisplayMember="major";
                comboBox2.ValueMember="majorId";
            }

2，

http://blog.csdn.net/gaofeng2000/archive/2009/05/06/4156247.aspx

ComboBox的SelectionChangeCommitted事件

实现方案：

 在ComboBox的SelectionChangeCommitted事件 写 联动取数：

  private  void comBox_subject_SelectionChangeCommitted(object sender, System.EventArgs e)
        {
            if (comBox_subject.SelectedIndex > -1)
            {
                DataRowView drv = (DataRowView)comBox_subject.SelectedItem;
                String check_subject = drv.Row["学科"].ToString();

                string connectionStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + System.Windows.Forms.Application.StartupPath + "/teachdb.mdb";
                OleDbConnection conn = new OleDbConnection(connectionStr);
                conn.Open();

                string strsubject = "select distinct 出版社 from presstable where 学科='" + check_subject + "'";
                OleDbDataAdapter MyAdapter1 = new OleDbDataAdapter(strsubject, conn);

                DataSet ds = new DataSet();
                MyAdapter1.Fill(ds, "press");

                comBox_Press.DataSource = ds.Tables["press"].DefaultView;
                comBox_Press.DisplayMember = "出版社";
                comBox_Press.ValueMember = "出版社";

                conn.Close();

            }
        }

 3

http://www.cnblogs.com/luoht/archive/2010/02/25/1673737.html

两个ComboBox互相联动的一种解决方法

今天工作中遇到一个头疼到问题就是两个comboBox互相联动绑定，开始用comboBox1_SelectedIndexChanged事件，结果两个comboBox不停的相互绑定，死循环了

后来发现微软还提供了一个comboBox1_DropDownClosed事件：当关闭组合框下拉部分时发生，当用程序改变SelectedIndex时就不会出现两个comboBox相互改对方到Index并触发comboBox1_SelectedIndexChanged，

后来将SelectedIndexChanged事件全部换成DropDownClosed，就可以实现两个comboBox互相联动了；

TextChanged事件和TextUpdate也是一个对用程序改变其值敏感，一个不敏感。