Display all products and products from category using QueryString asp.net

For all products do

<li><a href="Furniture.aspx?h_name=all">Electric</a></li>

Now in code add checking

string sql = "";
If Request.QueryString["h_name"] != "all"
{
//product based on h_name
sql = "select * from products where h_name=@h_name";
cmd.Parameters.AddWithValue("@h_name", Request.QueryString["h_name"]);
}
else
{
//All products
sql = "select * from products";
}

I managed to make a generic function for you

private void BindDataList(SqlConnection _cn, string query, List<KeyValuePair<string, object>> parameters, DataList dl)
    {
        SqlCommand _cmd = new SqlCommand(query, _cn);
        _cmd.CommandType = CommandType.StoredProcedure;
        if (parameters != null)
        {
            for (int i = 0; i < parameters.Count; i++)
            {
                _cmd.Parameters.AddWithValue(parameters[i].Key, parameters[i].Value);
            }
        }
        _cn.Open();
        SqlDataReader _dr = _cmd.ExecuteReader();
        if (_dr.HasRows)
        {
            dl.DataSource = _dr;
            dl.DataBind();
        }
    }

To call

//with Parameters
        List<KeyValuePair<string, object>> parameters = new List<KeyValuePair<string,object>>();
        KeyValuePair<string, object> keyValuePair = new KeyValuePair<string,object>("@h_name", Request.QueryString["h_name"]);
        parameters.Add(keyValuePair);
        BindDataList(_cn, "select * from products where h_name=@h_name", keyValuePair, DataList1);

        //without Parameters
        BindDataList(_cn, "select * from products", null, DataList2);