用C#读SQL SERVER到控制台的简单示例

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
namespace ConsoleApplication4
{
class Program
{
static void Main(string[] args)
{
//sqlserver身份验证
//string sqlconn = "server=(local);database=keede1228;user id=sa;password=123;";
//windows身份验证
string sqlconn = "server=(local);database=keede1228;integrated security=SSPI;";
string select = "select * from dbo.lmShop_City";
SqlConnection conn = new SqlConnection(sqlconn);
Console.WriteLine("33");
conn.Open();
Console.WriteLine("11");
SqlCommand cmd = new SqlCommand(select, conn);
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
Console.WriteLine("cityid:{0} city:{1} area:{2}", reader[0], reader[1], reader[2]);
}
conn.Close();
Console.WriteLine("22");
Console.ReadKey();
}
}
}

有一点疑问：最后输出到控制台的时候，如果不加"cityid:{0} city:{1} area:{2}"就会报错，不知道是为什么，好像是类型转换的事，有明白的帮我解答一下，谢谢。