using System;
using System.Collections.Generic;
using
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace 数据库登陆注册
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            SqlConnection mysql = new SqlConnection();
            mysql.ConnectionString = "server=USER-066E82BD8E\\SPF;Trusted_Connection=yes;database=pubs";
            mysql.Open();
            string selectStr = "select * from userwhere username = " +"'" + this.textBox1.Text + "and password=" + "'" + this.textBox2.Text + "'";
            SqlCommand cmd = new SqlCommand(selectStr, mysql);
            SqlDataReader dr = cmd.ExecuteReader();
            if(dr.Read())
                MessageBox.Show(this,"登陆成功!");
            else
                MessageBox.Show(this,"登陆失败!");
            mysql.Close();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            SqlConnection myconn = new SqlConnection("server =USER-066E82BD8E\\SPF;Trusted_Connection=yes;database=pubs");
            myconn.Open();
            MessageBox.Show(this, "OK");
            myconn.Close();
        }

      
    }
}

where and那边有错 ...不知道怎么改

你比我强多了，找到答案别忘了告诉兄弟一声谢谢