关于C#：SQL数据集问题

Problem with dataset to sql

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{
string selectDesc = @" SELECT [Descripion id], [Sub Collection FROM Descripion ";

DataSet dsD = new DataSet();
SqlCommand comD = new SqlCommand();
comD.Connection = con;
comD.CommandText = selectDesc;
SqlDataAdapter daD = new SqlDataAdapter();
daD.SelectCommand = comD;
SqlCommandBuilder cbD = new SqlCommandBuilder(da);
daD.Fill(dsD,"Descripion");
DataRow new_row_Desc = dsD.Tables[0].NewRow();
new_row_Desc["Descripion id"] = 58589;
new_row_Desc["Sub Collection"] = TextBox18.Text;
dsD.Tables[0].Rows.Add(new_row_Desc);
daD.Update(dsD.Tables[0]);
}

我收到此错误：

Update requires a valid InsertCommand when passed DataRow collection with new rows.

出什么问题了？