Gridview 找控制項 的兩個方法

Gridview 裡面有兩個下拉控制項
這兩個控制像分別有事件   透過  parent 找控制項  跟  NamingContainer 找控制項

protected void ddlWSEQ_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList ddlWSEQ = (DropDownList)sender;
        TextBox txtSYEAR = ddlWSEQ.Parent.FindControl("txtSYEAR") as TextBox;

    }


 protected void ddlITEM_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList ddlITEM2 = sender as DropDownList;
        TextBox txtBELONGITEM = ddlITEM2.NamingContainer.FindControl("txtBELONGITEM") as TextBox;
        txtBELONGITEM.Text = ddlITEM2.SelectedValue;
    }