你每次取出的是表中的首条记录,当然只能用首条记录登陆了!
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Dim name, password As String
name = TextBox1.Text
Dim com As New OleDb.OleDbCommand("select * from denglu where name='" name "'", conn)
Dim dr As OleDb.OleDbDataReader
conn.Open()
dr = com.ExecuteReader
dr.Read()
password = dr.GetString(1)
If TextBox3.Text = password Then
mesbox("成功!")
Else
msgbox("失败")
End If
dr.Close()
conn.Close()
这种情况下,效率极不好!你能理解什么意思就行了!否则将你的程序改完了!
代码如下:
/// summary
/// 连接到窗体:通过密码保护信息找回密码!
/// /summary
/// param name="sender"/param
/// param name="e"/param
private void lbl_mibao_Click(object sender, EventArgs e)
{
Getbackpwd getbackpwd = new Getbackpwd();
getbackpwd.Show();
}
/// summary
/// 当该窗体加载时从xml文件中读取用户信息并加载到combox的Items中
/// /summary
/// param name="sender"/param
/// param name="e"/param
private void Addresslist_Load(object sender, EventArgs e)
{
XmlTextReader reader = new XmlTextReader(@"E:\面向对象--C#练习\通讯录\address list\address list\user.xml");
while (reader.Read())
{
//if (reader.LocalName.Equals("Name") || reader.LocalName.Equals("Number"))
if (reader.LocalName.Equals("username"))
{
this.cmbUserName.Items.Add(reader.ReadString());
}
//if (reader.LocalName.Equals("Number"))
//{
// this.label2.Text += reader.ReadString() + "\n";\
//}
}
reader.Close();
}
/// summary
/// 保存用户名到user.xml
/// /summary
//在listcontol上更改SelectedValue时执行从数据库读取密码的事件
private void cmbUserName_SelectedValueChanged(object sender, EventArgs e)
{
string username = cmbUserName.Text.Trim();
string sql = string.Format("select pwd from Admin where Username='{0}'", username);
try
{
SqlCommand command = new SqlCommand(sql, DBHelper.connection);
DBHelper.connection.Open();
SqlDataReader dataReader = command.ExecuteReader();
while (dataReader.Read())
{
txtpwd.Text = (string)dataReader["pwd"];
checkBoxpwd.Checked = true;
}
}
catch
{
MessageBox.Show("数据库操作出错!");
}
finally
{
DBHelper.connection.Close();
}
}
/// summary
/// 记住密码操作
/// /summary
/// param name="sender"/param
/// param name="e"/param
private void checkBoxpwd_Enter(object sender, EventArgs e)
{
bool check = true;
check = checkinput(cmbUserName.Text.Trim());
if ((string)cmbUserName.Text.Trim() == "")
{
MessageBox.Show("请输入用户名", "输入提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
cmbUserName.Focus();
}
else
{
if (txtpwd.Text.Trim() == "")
{
MessageBox.Show("请输入密码", "输入提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
txtpwd.Focus();
}
else
{
bool isValidUser = false; // 标识是否为合法用户
string message = ""; // 如果登录失败,显示的消息提示
// 如果验证通过,就显示相应的用户窗体,并将当前窗体设为不可见
if (ValidateInput())
{
// 调用用户验证方法
isValidUser = ValidateUser(cmbUserName.Text, txtpwd.Text, ref message);
// 如果是合法用户,显示相应的窗体
if (isValidUser)
{
if (check == true)
{
XmlDocument doc = new XmlDocument();
doc.Load(@"E:\面向对象--C#练习\通讯录\address list\address list\user.xml");//(@"E:\面向对象--C#练习\通讯录\address list\address list\user.xml");
XmlElement node = doc.CreateElement("user");
XmlNode xnode = (XmlNode)doc.CreateElement("username");
xnode.InnerText = cmbUserName.Text.Trim();
node.AppendChild(xnode);
doc.DocumentElement.InsertAfter(node, doc.DocumentElement.LastChild);
doc.Save(@"E:\面向对象--C#练习\通讯录\address list\address list\user.xml");
//doc.Load (@"E:\面向对象--C#练习\通讯录\address list\address list\user.xml");
}
}
// 如果登录失败,显示相应的消息
else
{
MessageBox.Show(message, "记住密码失败!", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
}
}
}
}
/// summary
/// 验证当前combox中内容是否已经存在于xml文件中
/// /summary
/// param name="text"/param
/// returns/returns
private bool checkinput(string text)
{
int count;
bool c = true;
for (count = 0; count cmbUserName.Items.Count;count ++ )
{
if (text ==(string )cmbUserName .Items [count])
{
c=false;
}
}
return c;
}
xml文件内容如下:?xml version="1.0" encoding="utf-8"?
person
user
Private Sub Button _Click(ByVal sender As System Object ByVal e As System EventArgs) Handles Button Click
If TextBox Text = Or TextBox Text = Then
Label Text = 请确认您的输入!
Return
End If
Dim sql As String = select * from pwd where stu_id=@stu_id and pwd=@pwd
Dim m As SqlCommand = New SqlCommand(sql conn)
m Parameters Add(New SqlParameter( @stu_id SqlDbType Int ))
m Parameters( @stu_id ) Value = TextBox Text
m Parameters Add(New SqlParameter( @pwd SqlDbType Char ))
m Parameters( @pwd ) Value = TextBox Text
Dim dr As SqlDataReader
conn Open()
dr = m ExecuteReader
If dr Read Then
Session( stu_id ) = TextBox Text
dr Close()
m Cancel()
Dim sql_ As String = update stu_base set point=point+ where stu_id=@stu_id
m = New SqlCommand(sql_ conn)
m Parameters Add(New SqlParameter( @stu_id SqlDbType Int ))
m Parameters( @stu_id ) Value = Session( stu_id )
m ExecuteNonQuery()
m Cancel()
Response Redirect( detail aspx?stu_id= Session( stu_id ) )
Else
Label Text = 您还没有注册或账号密码错误
End If
End Sub
Private Sub Button _Click(ByVal sender As System Object ByVal e As System EventArgs) Handles Button Click
TextBox Text =
TextBox Text =
lishixinzhi/Article/program/net/201311/13960
哈哈简单哪
第一步:登陆网页代码
第二步:登陆以后判断是否登陆成功
有两种方法:1.获取网页代码,判断网页字符有无”登陆成功”字样
源代码:
2.就是判断网页是否跳转到了某一页
源代码:
两种方法结合起来用,可以判断网页是否无法连接
Dim conn As SqlConnection
Dim cn As New SqlConnection("Data Source=(local);Initial Catalog=用户登录;" "Integrated Security=true") '链接数据库
你这里初始化了的CONNECTION其实是CN,不是CONN,
所以
Dim login As New SqlCommand(sqlstr, conn)
这里应该是
Dim login As New SqlCommand(sqlstr, cn)