<1>一個簡單的使用者登陸

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
using System.Data;
namespace ConsoleApplication1
{
    class Program
    {
        //int errorPaw = 0;
        static void Main(string[] args)
        {
            string strConn = "Data Source=Fan-VAIO;InitialCatalog=sales;Integrated Security=True";
            Program pr = new Program();
            Console.WriteLine("請輸入使用者名稱：");
            string userName = Console.ReadLine();
            Console.WriteLine("請輸入密碼：");
            string userPaw = Console.ReadLine();
            using (SqlConnection conn = new SqlConnection(strConn))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "select * from t_user where name='" + userName + "'";
                    SqlDataReader reader = cmd.ExecuteReader();

                    if (reader.Read())
                    {
                        string adoPaw = reader.GetString(reader.GetOrdinal("password"));
                        if (userPaw == adoPaw)
                        {
                            Console.WriteLine("登陸成功");
                        }

                        else
                        {
                            Console.WriteLine("密碼錯誤,請輸入正確的密碼");
                        }

                        // pr.errorPaw++;

                        Console.WriteLine("請輸入密碼");
                        userPaw = Console.ReadLine();
                        if (userPaw == adoPaw)
                        {
                            Console.WriteLine("登陸成功");
                        }
                        else
                        {
                            Console.WriteLine("密碼錯誤,請輸入正確的密碼");
                        }
                        //pr.errorPaw++;
                        //pr.ErrorPaw();

                        Console.WriteLine("請輸入密碼");
                        userPaw = Console.ReadLine();
                        if (userPaw == adoPaw)
                        {
                            Console.WriteLine("登陸成功");
                        }
                        else
                        {
                            Console.WriteLine("密碼錯誤，因輸入次數過多，請稍後再試");
                            Console.ReadKey();
                            return;
                        }
                    }
                    else
                    {
                        Console.WriteLine("使用者名稱不存在");
                    }
                }
                Console.ReadKey();
            }
        }
    }
}