显示电子邮件中的列名和电子邮件的结构

所以我试图发送一封电子邮件与信息从数据库得到。我有一个问题，因为当我发送电子邮件的列名不显示。此外，我怎么能结构电子邮件显示像一个数据库的含义列名，并在它下的信息，然后下一列。下面是我的代码。正如你在底部看到的，我画了列。拉绳，但不工作。任何帮助都是感激的

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net.Mail;
using System.Net;
namespace sql_connection
{
class Program
{
 static void Main(string[] args)
{                             
    string conn = null;
    SqlConnection connection;
    conn= ("Data Source=database''SQL2012;Initial Catalog=jobs;User ID=user;Password=passs");
    connection = new SqlConnection(conn);
    try{
        connection.Open();
        Console.WriteLine("Connection Open!");
        SqlCommand cmd = new SqlCommand("SELECT [jobs].[dbo].[table hours].whd_Date,[jobs].[dbo].[table hours].whd_FromTime,[jobs].[dbo].[table hours].whd_ToTime, [jobs].[dbo].[table hours].whd_User,[jobs].[dbo].[table login].login_Email FROM [jobs].[dbo].[table hours]INNER JOIN [jobs].[dbo].[table login] ON [jobs].[dbo].[table hours].whd_User = [jobs].[dbo].[table login].login_LoginId WHERE  DATEDIFF(DAY,[whd_Date],GETDATE())<=7 AND   (whd_ToTime = '' OR whd_ToTime IS NULL) AND(whd_User=login_LoginId)");
        cmd.Connection = connection;
        SqlDataReader reader = cmd.ExecuteReader();
        var columns = Enumerable.Range(0, reader.FieldCount).Select(reader,GetName).ToList();

        var list = new List<string>();
        while(reader.Read())
        {

              var s = string.Format("{4},{3},{2}, {1}, {0}",
               reader["whd_ToTime"] == DBNull.Value? "NULL" : reader["whd_ToTime"].ToString(), 
               reader["whd_FromTime"] == DBNull.Value? "NULL" : reader  ["whd_FromTime"].ToString(), 
               reader["whd_Date"].ToString(), 
               reader["whd_User"].ToString(),
               reader["login_Email"].ToString());
              Console.WriteLine("'t", columns.ToArray()));
            Console.WriteLine(s);
            list.Add(s);


        }
        var sb = new StringBuilder();
        foreach (var s in list)
        {
            sb.AppendLine(s);
        }

        connection.Close();
         MailAddress to = new MailAddress("email@gmail.com");

        MailAddress from = new MailAddress("email@gmail.com");
        MailMessage mail = new MailMessage(from, to);

        mail.Subject = ("missed punch clock");
        mail.Body = sb.ToString(); columns.ToString();
        SmtpClient smtp = new SmtpClient();
        smtp.Host = "smtp.gmail.com";
        smtp.Port = 587;
        smtp.Credentials = new NetworkCredential(
            "email@gmail.com", "passworrd");
        smtp.EnableSsl = true;
        Console.WriteLine("Sending email..");
        smtp.Send(mail);
    } 


    catch (Exception ex)
    {
        Console.WriteLine(ex.Message);
    }                       
}
}
}

string columnNames = string.Join(',', columns);
mail.Subject = ("missed punch clock");        
mail.Body = String.Concat(sb.ToString(), columnNames );