将Combox显示的值设置到文本框上 如何做 我写的不行 高手指点 谢谢

Question

    private void Form1_Load(object sender, EventArgs e)
        {
            string connstr = "server=(local);uid=sa;pwd=ccxx;database=master";
            string sql = "select id,班级 from 班级1";
            using (SqlConnection conn = new SqlConnection(connstr))
            {
               
                try
                {
                    conn.Open();
               
                    SqlDataAdapter da = new SqlDataAdapter(sql, conn);                    DataTable dt = new DataTable();
              
                    da.Fill(dt); comboBox1.DataSource = dt;
                    comboBox1.DisplayMember = "班级";
                    comboBox1.ValueMember = "id"; 
                }
                catch (Exception ex)
                {                    throw new Exception(ex.Message);
                }
            }
        }        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            string selectindex = comboBox1.SelectedValue.ToString();
            textBox1.Text = selectindex;
        }        private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            //string selectindex = comboBox2.SelectedItem.ToString();
            //textBox1.Text = selectindex;
        }
   
    }简单说一下  如果用selectvalue  能得到combox的valuenumber  combobox2是写死的  用
selectitem可以显示在文本框  combobox1是从数据源获取的  用selectitem 显示的东西是System.Data.DataRowView

Answer 1

DataRowView drv = (DataRowView)comboBox2.SelectedItem
textBox1.Text  = drv["班级"].ToString()