asp.net刪除一行數據

前台的代碼：注意沒有使用sqldatasource

 <asp:GridView ID="GridView1" runat="server" AllowPaging="True" PageSize="6"  OnRowDeleting="GridView1_deleting"
    AutoGenerateColumns="False" DataKeyNames="用戶名"  Width="819px">
    <Columns>
        <asp:BoundField DataField="用戶名" HeaderText="用戶名" ReadOnly="True"
            SortExpression="用戶名" />
        <asp:BoundField DataField="密碼" HeaderText="密碼" SortExpression="密碼" />
        <asp:BoundField DataField="性別" HeaderText="性別" SortExpression="性別" />
        <asp:BoundField DataField="出生時間" HeaderText="出生時間" SortExpression="出生時間" />
        <asp:BoundField DataField="聯系方式" HeaderText="聯系方式" SortExpression="聯系方式" />
        <asp:BoundField DataField="郵箱" HeaderText="郵箱" SortExpression="郵箱" />
        <asp:BoundField DataField="密碼保護問題" HeaderText="密碼保護問題"
            SortExpression="密碼保護問題" />
        <asp:BoundField DataField="密碼保護問題回答" HeaderText="密碼保護問題回答"
            SortExpression="密碼保護問題回答" />
        <asp:BoundField DataField="注冊時間" HeaderText="注冊時間" SortExpression="注冊時間" />
        <asp:TemplateField ShowHeader="true" HeaderText="刪除用戶">
            <ItemTemplate>
                <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="False" CommandName="Delete"
                    Text="刪除" OnClientClick='<%#  "if (!confirm(\"你確定要刪除" + Eval("用戶名").ToString() + "嗎?\")) return false;"%>'></asp:LinkButton>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

 后台的代碼：

protected void Page_Load(object sender, EventArgs e)
   {
       if(!Page.IsPostBack)
       {
           bind();
       }
   }
   public void bind()
   {
       SqlConnection conn = new SqlConnection(CommonMethods.connstring);
       conn.Open();
       string cmd = "select * from userlogin";
       SqlDataAdapter da = new SqlDataAdapter(cmd, conn);
       DataSet ds = new DataSet();
       da.Fill(ds);
       GridView1.DataSource = ds;
       GridView1.DataBind();
       conn.Close();
   }

   protected void GridView1_deleting(object sender, GridViewDeleteEventArgs e)//注意各種事件的參數類型
   {
       SqlConnection conn = new SqlConnection(CommonMethods.connstring);
       conn.Open();
       string deleteuser = GridView1.DataKeys[e.RowIndex].Value.ToString();//獲取主鍵
       string cmd = "delete from userlogin where 用戶名='" + deleteuser+"'" ;//
       SqlCommand cmdt = new SqlCommand(cmd, conn);
       try
       {
           cmdt.ExecuteNonQuery();
           Response.Write("<script>alert('刪除成功！')</script>");
       }
       catch
       {
           return;
       }
       bind();
       conn.Close();
   }