To avoid data to show in a datalist

Question

I want to show some data by datalist. But some of them have to avoid.
That is I want to show data without some data.
Clearly I want to make a friend list so I have to show users from data base.
But some friend who are already friend with him are not to show.
So how can I avoid this users to show in add friend list.

Answer 1

 <asp:DataList ID="DataList1" runat="server" DataSourceID="SqlDataSource1" style="margin-left: 185px">
                    <ItemTemplate>
                        <table class="auto-style2">
                    <tr>
                        <td><asp:Label ID="fnameLabel" runat="server" Text='<%# Eval("fname") %>' />
                        <asp:Label ID="lnameLabel" runat="server" Text='<%# Eval("lname") %>' /></td>
                        <td style="text-align:right"><asp:Button Text="Add as friend" ID="btnAddFriend" CommandArgument='<%# Eval("username") %>' 
                    OnClick="btnAddFriend_Click" runat="server" /></td>
                    </tr>
                </table>
                    </ItemTemplate>
                </asp:DataList>
                <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:dbcon %>" SelectCommand="SELECT [fname], [lname],[username] FROM [Users]"></asp:SqlDataSource>
And this is the button function
protected void btnAddFriend_Click(object sender, EventArgs e)
        Button btnAddFriend = sender as Button;
        string userId = btnAddFriend.CommandArgument;
        using (SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["dbcon"].ToString()))
            cn.Open();
            String S = Session["user"].ToString();
            SqlCommand cmd1 = new SqlCommand("INSERT INTO Friend  values('" + Session["user"].ToString() + "','" + userId + "','pending')", cn);
            SqlDataReader rdr = cmd1.ExecuteReader(CommandBehavior.CloseConnection);
            cn.Close();