我在dataGrid中通过form_load显示查询结果后，打算通过按钮对查询结果更新，可是按钮下的代码怎么写不对，郁闷好几天了，恳请大家帮忙～～～下面是form_load中的代码：
myConnection = new SqlConnection("Integrated Security=sspi;initial Catalog =Fnew;Data Source=JYK1");
String selectCmd = "select * from songy where number=@number";

myCommand=new SqlDataAdapter(selectCmd,myConnection);

myCommand.SelectCommand.Parameters.Add(new SqlParameter("@number", SqlDbType.Char));
myCommand.SelectCommand.Parameters["@number"].Value ="001";
DataSet ds=new DataSet();
myTable=new DataTable();
myCommand.Fill(ds,"myTable");

this.dataGrid1.DataSource = this.ds["myTable"];

大家帮我分析一下我的错误：
未处理的“System.InvalidOperationException”类型的异常出现在 system.data.dll 中。

其他信息: Update 无法找到 TableMapping['songy'] 或 DataTable“songy”

private void button1_Click(object sender, System.EventArgs e)
{
string conStr,updateCmd;
conStr="Integrated Security=sspi;initial Catalog =Fnew;Data Source=JYK1";
updateCmd="UPDATE songy SET name = @name" + "WHERE number = @number";
SqlConnection con=new SqlConnection(conStr);
System.Data.SqlClient.SqlDataAdapter md=new SqlDataAdapter(updateCmd,con);
DataSet ds=new DataSet();

md.Update(ds,"songy");
this.dataGrid1.DataSource=ds.Tables["songy"].DefaultView;
this.dataGrid1.SetDataBinding(ds,"songy");