哪异常

求助 哪错误
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;

namespace mdf
{
  class Program
  {
  static void Main(string[] args)
  {
  SqlConnection conn = new SqlConnection();
  conn.ConnectionString =@"Data source=.\;Initial Catalog=lianxi;User ID=sa;Password=fengjianhua";
  conn.Open();
  SqlCommand cmd = new SqlCommand();
  cmd.CommandText = "insert into fjh(name) values ('abf')";
  cmd.ExecuteNonQuery();----------------提示：ExecuteNonQuery: Connection 属性尚未初始化。
  Console.WriteLine("插入成功");
  Console.WriteLine("连接成功");
  Console.ReadKey();
  }
  }
}


[解决办法]
conn.ConnectionString =@"Data source=.\;Initial Catalog=lianxi;User ID=sa;Password=fengjianhua";
==========
 conn.ConnectionString =@"Data source=.;Initial Catalog=lianxi;User ID=sa;Password=fengjianhua";
[解决办法]
如果数据库是EXPRESS版本的话：
Data source=./sqlexpress
[解决办法]
sorry

 SqlCommand cmd = new SqlCommand(conn );
[解决办法]
SqlConnection conn = new SqlConnection();
conn.ConnectionString =@"Data source=.\;Initial Catalog=lianxi;User ID=sa;Password=fengjianhua";
=>

SqlConnection conn = new SqlConnection("server=.;database=lianxi;uid=sa;pwd=fengjianhua");
[解决办法]
sorry

 SqlCommand cmd = new SqlCommand(conn );
[解决办法]
改成这样：

C# code

conn.ConnectionString =@"Data source=(local);Initial Catalog=lianxi;User ID=sa;Password=fengjianhua";
[解决办法]
 SqlConnection conn = new SqlConnection();
 conn.ConnectionString =@"Data source=.;Initial Catalog=lianxi;User ID=sa;Password=fengjianhua";
 conn.Open();
  SqlCommand cmd = new SqlCommand("insert into fjh(name) values ('abf')",conn);    cmd.ExecuteNonQuery(); 
 Console.WriteLine("插入成功");
 Console.WriteLine("连接成功");
 Console.ReadKey();