Unable to fetch data from database

protected void Page_Load(object sender, EventArgs e)
{
   GetResults();
}

private void GetResults()
{
   SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["HousingConnectionString"].ConnectionString);
   conn.Open();
   string query;
   SqlCommand com;
   SqlDataReader reader;

   SqlDataAdapter adapter = new SqlDataAdapter();

   query = "SELECT Flat, First_Name, Middle_Name, Last_Name, Mobile_No, Email, DOB, Age, Education, Office_Add, Native_Add, PAN_Card, Aadhar_Card, Religion, Business_Job, Married_Unmarried, No_Of_Members, Joining_Date from Primary_Member where Flat='" + Request.QueryString["fnum"] + "'";

   com = new SqlCommand(query, conn);
   adapter.SelectCommand = new SqlCommand(query, conn);
   reader = com.ExecuteReader();
   GridView1.DataSource = reader;
   GridView1.DataBind();
}