public void Form4_Load(object sender, EventArgs e)
  {

  sqlexe sqlexe=new sqlexe();

  string sqlword = "select * from room";

  sqlhelper sqldata = new sqlhelper();//实例化sqlhelper类，再调用类里的sqlconn 调用数据连接字符串

  string strconn = sqldata.sqlconnstr;

  SqlConnection conn = new SqlConnection(strconn); //建立数据库连接

  conn.Open(); //连接数据

  SqlCommand cmd = new SqlCommand(); //创建sqlcommand对象

  cmd.Connection = conn; //指定使用conn链接数据库

  cmd.CommandText = sqlword;

  cmd.CommandType = CommandType.Text;

  SqlDataAdapter sda = new SqlDataAdapter();

  sda.SelectCommand = cmd;

  DataSet ds = new DataSet();

  sda.Fill(ds);

  dataGridView1.DataSource = ds.Tables[0];

  conn.Close();

  //return sda;

  ////////////////////////////////////

    
  }
public void button1_Click(object sender, EventArgs e)
  {
    
  sqlexe sqlexe = new sqlexe();

  string sqlword = "select * from room";

  sqlhelper sqldata = new sqlhelper();//实例化sqlhelper类，再调用类里的sqlconn 调用数据连接字符串

  string strconn = sqldata.sqlconnstr;

  SqlConnection conn = new SqlConnection(strconn); //建立数据库连接

  conn.Open(); //连接数据

  SqlCommand cmd = new SqlCommand(); //创建sqlcommand对象

  cmd.Connection = conn; //指定使用conn链接数据库

  cmd.CommandText = sqlword;

  cmd.CommandType = CommandType.Text;

  SqlDataAdapter sda = new SqlDataAdapter();

  sda.SelectCommand = cmd;

  DataSet ds = new DataSet();

  sda.Fill(ds);

  SqlCommandBuilder objBuilder = new SqlCommandBuilder(sda);

  sda.Update(ds);

  ds.AcceptChanges();

  MessageBox.Show("success");

  }
 public class sqlhelper //连接数据库文件sql语句
  {
  public string sqlconnstr="Data Source=.\\SQLEXPRESS;User id=sa12;Pwd=12;database=wj"; //选择正确的数据库
  }