【2017-04-24】winform基础、登录窗口、窗口属性

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;

namespace WindowsFormsApplication1.App_Code
{
    public class UsersData
    {
        SqlConnection conn = null;
        SqlCommand cmd = null;

        public UsersData()
        {
            conn = new SqlConnection("server=.;database=Data0216;user=sa;pwd=123");
            cmd = conn.CreateCommand();
        }

        //查询是否存在该帐号
        public bool SelectHasName(string name)
        {
            bool has = false;
            cmd.CommandText = "select * from Users where UserName=@a";
            cmd.Parameters.Clear();
            cmd.Parameters.AddWithValue("@a",name);
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();

            if (dr.HasRows)
            {
                has = true;
            }

            conn.Close();
            return has;
        }
    
    
    //如果存在，查询该用户下对应的密码
        public string SelectPassWord(string name)
        {
            string end="";

            cmd.CommandText = "select PassWord from Users where UserName=@a";
            cmd.Parameters.Clear();
            cmd.Parameters.AddWithValue("@a",name);

            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            dr.Read();
            end = dr["PassWord"].ToString();
            conn.Close();

            return end;
        }  
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using WindowsFormsApplication1.App_Code;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string username = textBox1.Text;
            string password = textBox2.Text;


            UsersData ud = new UsersData();
            bool HasName = ud.SelectHasName(username);
            
            //如果帐号存在
            if (HasName)
            {
                //查询该帐号对应的密码是否与用户输入的一致
                if (password == ud.SelectPassWord(username))
                {
                    MessageBox.Show("帐号密码匹配成功！");
                }
                else MessageBox.Show("您输入的密码不正确！");
            }

            else MessageBox.Show("您输入的账户不存在！");

        }
    }
}