if (!IsPostBack)
        {
            using (UsersDataContext con = new UsersDataContext())
            {
                Repeater1.DataSource = con.Users.ToList();
                Repeater1.DataBind();
            }
        }

    void Button1_Click(object sender, EventArgs e)
    {
       Label1.Text=Request["ck"];
    }

 <asp:Button ID="Button1" runat="server" Text="Button" />
            <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>


            <table style="background-color: navy; text-align: center;">
                <tr style="color: white; font-size: 20px;">
                    <%--全选用的纯元素--%>
                    <td>
                        <input type="checkbox" id="ckall" /><label for="ckall">全选</label></td>
                    <td>编号</td>
                    <td>用户名</td>
                </tr>

                <asp:Repeater ID="Repeater1" runat="server">
                    <ItemTemplate>
                        <tr style="background-color: white;">
                            <td>
                                <%--单选用的纯元素--%>
                                <input type="checkbox" name="ck" value=http://www.mamicode.com/‘<%#Eval("Ids") %>‘ /></td>
                            <td><%#Eval("Ids") %></td>
                            <td><%#Eval("username") %></td>
                        </tr>
                    </ItemTemplate>
                </asp:Repeater>
            </table>

<script type="text/javascript">
    var ckall = document.getElementById("ckall");
    var cks = document.getElementsByName("ck");
    ckall.onclick = function () {

        for (var i = 0; i < cks.length; i++) {
            cks[i].checked = this.checked;
        }
    }

    for (var i = 0; i < cks.length; i++) {
        var count = 0;
        for (var j = 0; j < cks.length; j++) {
            //假设有一个 没选  count +1
            if (cks[j].checked == false)
                count++;
        }
        //都选   全选  选中状态
        if (count == 0) {
            ckall.checked = true;
        }
        else {

            ckall.checked = false;
        }

    }


</script>