asp.net删除一行数据

前台的代码：注意没有使用sqldatasource

 <asp:GridView ID="GridView1" runat="server" AllowPaging="True" PageSize="6"  OnRowDeleting="GridView1_deleting"
    AutoGenerateColumns="False" DataKeyNames="用户名"  Width="819px">
    <Columns>
        <asp:BoundField DataField="用户名" HeaderText="用户名" ReadOnly="True"
            SortExpression="用户名" />
        <asp:BoundField DataField="密码" HeaderText="密码" SortExpression="密码" />
        <asp:BoundField DataField="性别" HeaderText="性别" SortExpression="性别" />
        <asp:BoundField DataField="出生时间" HeaderText="出生时间" SortExpression="出生时间" />
        <asp:BoundField DataField="联系方式" HeaderText="联系方式" SortExpression="联系方式" />
        <asp:BoundField DataField="邮箱" HeaderText="邮箱" SortExpression="邮箱" />
        <asp:BoundField DataField="密码保护问题" HeaderText="密码保护问题"
            SortExpression="密码保护问题" />
        <asp:BoundField DataField="密码保护问题回答" HeaderText="密码保护问题回答"
            SortExpression="密码保护问题回答" />
        <asp:BoundField DataField="注册时间" HeaderText="注册时间" SortExpression="注册时间" />
        <asp:TemplateField ShowHeader="true" HeaderText="删除用户">
            <ItemTemplate>
                <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="False" CommandName="Delete"
                    Text="删除" OnClientClick='<%#  "if (!confirm(\"你确定要删除" + Eval("用户名").ToString() + "吗?\")) return false;"%>'></asp:LinkButton>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

 后台的代码：

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)//注意各种事件的参数类型
   {
       SqlConnection conn = new SqlConnection(CommonMethods.connstring);
       conn.Open();
       string deleteuser = GridView1.DataKeys[e.RowIndex].Value.ToString();//获取主键
       string cmd = "delete from userlogin where 用户名='" + deleteuser+"'" ;//
       SqlCommand cmdt = new SqlCommand(cmd, conn);
       try
       {
           cmdt.ExecuteNonQuery();
           Response.Write("<script>alert('删除成功！')</script>");
       }
       catch
       {
           return;
       }
       bind();
       conn.Close();
   }