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;namespace MyUser
{
public partial class frmLogin : Form
{
public frmLogin()
{
InitializeComponent();
}
//关闭事件
private void btnCancle_Click(object sender, EventArgs e)
{
Application.Exit();
}
//登陆事件--进入主窗体
private void btnOK_Click(object sender, EventArgs e)
{
if (txtName.Text.Trim().Length==0)
{
MessageBox.Show("请输入账号", "小念提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
else if (txtPwd.Text.Trim().Length==0)
{
MessageBox.Show("请输入密码", "小念提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
else if (txtName.Text.Trim().Length>0&&txtPwd.Text.Trim().Length>0)
{
string sql = string.Format("select * from Users where Uname='{0}' and Upwd='{1}'", txtName, txtPwd);
int result = (int)DBHelper.SelectForScaler(sql);
if (result==1)
{
frmMain main = new frmMain();
main.Show();
}
}
}
}
}很简单的代码 可是提示未将对象引用设置到对象的实例,大家帮我看看那,谢谢
这里
int result = (int)DBHelper.SelectForScaler(sql);
DBHelper.SelectForScaler为null值,转换int时出错
要看DBHelper.SelectForScaler为什么返回null,或者返回null就不要转了