gridview更新问题！

   sqlcon = new SqlConnection(strCon);



 string sqlstr = "update users set pe_user='" + ((TextBox)(GridView1.Rows[e.RowIndex].Cells[1].Controls[0])).Text.ToString().Trim() + "',pe_pwd='" + ((TextBox)(GridView1.Rows[e.RowIndex].Cells[2].Controls[0])).Text.ToString().Trim() + "'where pe_userid='" + GridView1.DataKeys[e.RowIndex].Value.ToString() + "'";
           (无法将类型为“System.Web.UI.LiteralControl”的对象强制转换为类型“System.Web.UI.WebControls.TextBox”。)

 sqlcom = new SqlCommand(sqlstr, sqlcon);
            sqlcon.Open();
            sqlcom.ExecuteNonQuery();
            sqlcon.Close();
            GridView1.EditIndex = -1;
            bind();
就是上面出问题了   求助啊   把.Text.ToString().Trim该为那什么也不对    不知道怎么弄了