C#怎么连接SQL 2000

using(sqlconnect conn = new sqlconnect("server=.;pwd = 'sa',user id = 'sa',database = Northwind"))
{
  conn.open();
  sqlcommand cmd = new  sqlcommand("SQl语句"，conn);
  
}

string  ConnectionString = "server=.;database=pubs;user=sa;pwd="; //这是获得连接数据库的字符串
using(SqlConnection conn = new SqlConnection(ConnectionString))
{
         conn.Open();              //创建连接数据库的对象并且打开数据库
         string  sqlstr= "SELECT * FROM authors";
         SqlCommand cmd = new SqlCommand(sqlstr,conn);                     //创建执行SQL语句的对象.注意两个参数
          = CommandType.Text;                             
         SqlDataReader reader = cmd.ExecuteReader();      
         while (reader.Read())
         {
              //每reader.Read()一下，就读取了一行数据，可以对这行数据进行操作了
         }
}

我用的是SQL 2005

try
            {
                SqlConnection conn = new SqlConnection("server=.;pwd = 'sun',user id = 'sa',database = db");

                conn.Open();

                SqlCommand cmd = new SqlCommand();

                = "INSERT INTO test(city,tq,wd) VALUES ('qq','" + YQ + "','" + WD + "')";

                cmd.Connection = conn;

                cmd.EndExecuteNonQuery();//这里提示错误，应该是数据库连接问题

                MessageBox.Show("数据添加成功!");

                conn.Close();
            }
            catch (SqlException E)
            {
                MessageBox.Show(E.Message);
            }