麻烦会的大神帮忙注释一上，新手不懂！

麻烦会的大神帮忙注释一下，新手不懂！！！！！
SqlConnection conn = new SqlConnection();//实例化对象
  string conStr = @"Data Source=WHIZENDT016\SQLEXPRESS;Initial Catalog=Users;Integrated Security=True";
  conn.ConnectionString = conStr;
  conn.Open();
  SqlCommand cmd = new SqlCommand("select * from Users_id where Id='" + textBox1.Text + "'and Password ='" + textBox2.Text + "'", conn);
  SqlDataReader str = cmd.ExecuteReader();
  str.Read();

[解决办法]

C# code

           SqlConnection conn = new SqlConnection();//实例化对象            //數據庫連接字符串            string conStr = @"Data Source=WHIZENDT016\SQLEXPRESS;Initial Catalog=Users;Integrated Security=True";            conn.ConnectionString = conStr;            //打開連接            conn.Open();            //執行sql 命令            SqlCommand cmd = new SqlCommand("select * from Users_id where Id='" + textBox1.Text + "'and Password ='" + textBox2.Text + "'", conn);            //按READER方式執行查詢            SqlDataReader str = cmd.ExecuteReader();            //此次可循環READ，逐條取得結果            str.Read();