网页上的账号、密码登陆验证，是如何实现的？（二）比对数据库中的账号密码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;
using System.Data.SqlClient;
using System.Net;
namespace WindowsFormsApp2
{
    public partial class Form1 : Form
    {
        public static Form1 pForm1 = null;

        private SqlConnection master;//定义数据连接对象
        private SqlCommand cmd;//定义数据命令对象
        private SqlDataAdapter sqlada;//定义数据适配器对象
        private SqlCommandBuilder sqlbuid;//定义CommandBuilder对象
        private DataSet ds;//定义数据集对象
        public Form1()
        {
            pForm1 = this;
            
            InitializeComponent();
        }

        private void label7_Click(object sender, EventArgs e)
        {

        }

        private void txtCardNum_TextChanged(object sender, EventArgs e)
        {

        }

        private void btnOpenPort_Click(object sender, EventArgs e)
        {

            Form2 frm2 = new Form2();
            String textzhanghao = zhanghao.Text;
            String textmima = mima.Text;
            string zhanghao1;
            string mima1;
            string connString = "server=DESKTOP-=\\SQLEXPRESS; database=master;integrated security=SSPI";
            string sqlString = "select sno,sname from student where sno='" + textzhanghao + "'and sname='" + textmima + "' ";
            master = new SqlConnection(connString);
            master.Open();//打开连接
            SqlCommand sqlCommand = new SqlCommand(sqlString, master);
            SqlDataReader sqlDataReader = sqlCommand.ExecuteReader();

            if (sqlDataReader.HasRows)//满足用户名与密码一致，进入下一个界面
            {
                frm2.Show();
                this.Hide();
            }
            else
                MessageBox.Show("账号密码不正确");
          
        }

    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp2
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void Form2_Load(object sender, EventArgs e)
        {

        }
    }
}