how to read data when click on button event of datalist

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ASP.NET

Our design:-

<asp:DataList ID="DataList2" runat="server" Width="44%" BackColor="#FFFFCC"
              style="text-align: left" onitemcommand="DataList2_ItemCommand"  >
       <ItemTemplate>
         <table width="100%" border="1">
         <tr>
         <td width="100px">
          <asp:HiddenField runat="server" ID="hduser" Value='<%# Eval("username") %>' />
         <asp:Image ID="Image1" runat="server" ImageUrl = '<%# Eval("FilePath")%>'  BorderStyle="Ridge"  Width = "100px" Height = "100px"/>
         </td>
         <td>
         <span style="color:Red;font:14pt arial"><%# Eval("Name")%></span>
         <pre><span style="font:10pt Cambria"><%# Eval("city")%></pre>
         <%--<asp:Button ID="btnAddFriend" runat="server" Text="Add Friend"   CommandName="save"  />--%>
          <asp:LinkButton ID="LinkButton1" runat="server" CommandName="saverequest" CommandArgument='<%# Eval("username") %>' OnClick="populateSubCats">   </asp:LinkButton>
         </td>
         </tr>
         </table>
       </ItemTemplate>
   </asp:DataList>

code that i ma using:-
protected void DataList2_ItemCommand(object source, DataListCommandEventArgs e)
{
string username = string.Empty;
DataTable dtuser1 = (DataTable)Session["User"];
string user = dtuser1.Rows[0][1].ToString();


username = ((HiddenField)(e.Item.FindControl("username"))).Value;
String strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
SqlConnection con = new SqlConnection(strConnString);
string strQuery = "UPDATE [FriendTable] SET [Is_Approved] = 1 WHERE Touser ='" + user + "' and Fromuser ='" + username + "'";
SqlCommand cmd = new SqlCommand(strQuery);

cmd.CommandType = CommandType.Text;
cmd.Connection = con;
try
{
con.Open();
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
finally
{
con.Close();
con.Dispose();
}


}
pls reply me soon