一个简单的省市选择的例子

初学C#，于是写了一个省市选择的小例子，几经周折，调试成功，很有成就感，省、市都是存在数据库中的，通过combox来进行绑定，大家有么有什么更好的写法呢，分享出来交流交流

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

namespace 省市选择
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (cmBsheng.Text== "云南")
            {
                using (SqlConnection conn = new SqlConnection(@"Data Source=ZGC-20121026JVO;Initial Catalog=studentinfo;Integrated Security=True"))
                {
                    conn.Open();
                    SqlDataAdapter sda1 = new SqlDataAdapter("select shi from T_ynC", conn);
                    DataTable dt1 = new DataTable();
                    sda1.Fill(dt1);
                    cmBshi.DataSource = dt1;
                    cmBshi.DisplayMember = "shi";
                }
            }
            if (cmBsheng.Text == "山东")
            {
                using (SqlConnection conn = new SqlConnection(@"Data Source=ZGC-20121026JVO;Initial Catalog=studentinfo;Integrated Security=True"))
                {
                    conn.Open();
                    SqlDataAdapter sda1 = new SqlDataAdapter("select shi from T_sdC", conn);
                    DataTable dt1 = new DataTable();
                    sda1.Fill(dt1);
                    cmBshi.DataSource = dt1;
                    cmBshi.DisplayMember = "shi";
                }
            }
           
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            using(SqlConnection conn=new SqlConnection(@"Data Source=ZGC-20121026JVO;Initial Catalog=studentinfo;Integrated Security=True"))
            {
                conn.Open();
                SqlDataAdapter sda = new SqlDataAdapter("select sheng from T_S", conn);
                DataTable dt = new DataTable();
                sda.Fill(dt);
                cmBsheng.DataSource = dt;
                cmBsheng.DisplayMember = "sheng";
                cmBsheng.Text = "请选择省";
                cmBshi.Text = "请选择市";
              
            }
        }

        private void cmBshi_SelectedIndexChanged(object sender, EventArgs e)
        {
           
        }
    }
}