try
            {
                if (textBox1.Text == "")
                {
                    MessageBox.Show("用户名不能为空");
                }
                else
                {
                    if (textBox2.Text == "")
                    {
                        MessageBox.Show("密码不能为空!");
                    }
                    else
                    {
                            string admin_id = textBox1.Text;//获取账号
string admin_psw = textBox2.Text;//获取密码
                            string conn = "Data Source=LJQA2ILTGDR8QRN;Initial Catalog=admin_login;Integrated Security=True";//连接字符串，需要改成你自己的
                            SqlConnection connection = new SqlConnection(conn);//创建连接
                            connection.Open();//打开连接
                            string sql = string.Format("select count(*) from admin where admin_id='{0}' and admin_psw='{1}'", admin_id , admin_psw);//查询是否有该条记录，根据账户密码
                            SqlCommand command = new SqlCommand(sql, connection);//sqlcommand表示要向向数据库执行sql语句或存储过程
                            int i = Convert.ToInt32(command.ExecuteScalar

());//执行后返回记录行数
                            if (i > 0)//如果大于1，说明记录存在，登录成功
                            {
                                MessageBox.Show("登录成功！");
                                Form3 f3 = new Form3();
                                this.Close();
                                f3.ShowDialog();
                            }
                            else
                            {
                                MessageBox.Show("用户名或者密码错误！");
                            }
                            connection.Close();
                    }

                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("异常错误" + ex);
            }

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