Some sort of vague VB.NET/Access question

Question

1.00/5 (3 votes)

See more:

'Im using vb.net with access database ehhehe

VB

Try
    strSQL = "SELECT * FROM User WHERE (Username LIKE ?) AND (Password LIKE ?)"

    Dim dbCmd As New OleDbCommand(strSQL, conn)

    dbCmd.Parameters.AddWithValue("@Username", txtUsername.Text)
    dbCmd.Parameters.AddWithValue("@Password", txtPassword.Text)
    dbReader = dbCmd.ExecuteReader()


    Using dbReader
        If dbReader.Read() Then
            Dim strResult1 As String = dbReader.Item("Username")
            Dim strResult2 As String = dbReader.Item("Password")

            If chkRememberUsername.Checked = True Then
                My.Settings.Username = txtUsername.Text
                My.Settings.Save()
                My.Settings.Reload()

            End If

            Me.Close()
            mediaSoundPlayer.Stream = My.Resources.tada
            mediaSoundPlayer.Play()

            frmLoading.ShowDialog()

            'frmMain.LogOffToolStripMenuItem.Text = "Log Off"
            'frmMain.SettingToolStripMenuItem.Enabled = True
            frmMain.LogOffToolStripMenuItem.Text = "Log Off"
            Me.Close()
            frmMain.Show()
        Else

            intResult = MessageBox.Show("Invalid Username Or Password", "Login", MessageBoxButtons.RetryCancel, MessageBoxIcon.Error)


            If intResult = DialogResult.Cancel Then
                Me.Close()

            Else
                intResult = DialogResult.Retry
                Me.Show()

            End If
            frmMain.SettingsToolStripMenuItem.Enabled = False
            frmMain.LogOffToolStripMenuItem.Text = "Login"


        End If


    End Using
    conn.Close()

Catch ex As Exception
    MsgBox("System Error", MsgBoxStyle.Critical, "Error in login")
End Try

Posted 15-Feb-10 5:00am

xiroH4ck3r

Updated 17-Feb-10 11:46am

Christian Graus

v3

Add a Solution

6 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

William Winner · Answer 1 · 2010-02-17T06:16:00

If you're using question marks, it should be formatted more like:

VB

cmd1.CommandText = "SELECT ID FROM Employee "
                 + "WHERE id BETWEEN ? AND ?";
OleDbParameter p1 = new OleDbParameter();
OleDbParameter p2 = new OleDbParameter();
cmd1.Parameters.Add(p1);
cmd1.Parameters.Add(p2);
p1.Value = "01";
p2.Value = "03";

If you're using AddWithValue, it should be like:

VB

Dim SqlString As String = "Select * From Contacts Where FirstName = ? And LastName = ?"

Using conn As New OleDbConnection(ConnString)

  Using cmd As New OleDbCommand(SqlString, conn)

    cmd.CommandType = CommandType.Text

    cmd.Parameters.AddWithValue("FirstName", txtFirstName.Text)

    cmd.Parameters.AddWithValue("LastName", txtLastName.Text)

If you want to use the @ symbol, then it's set up differently...

Dim SqlString As String = "Select * From Contacts Where FirstName = @FirstName And LastName = @LastName"

Using conn As New OleDbConnection(ConnString)

  Using cmd As New OleDbCommand(SqlString, conn)

    cmd.CommandType = CommandType.Text

    cmd.Parameters.AddWithValue("FirstName", txtFirstName.Text)

    cmd.Parameters.AddWithValue("LastName", txtLastName.Text)

Some of this is from: Parameter Queries in ASP.NET with MS Access[^]
and some is from: Pass Parameter to OleDbCommand[^]

Hopefully the others didn't confuse you, but you're mixing the styles around...as were they.

William Winner · Answer 2 · 2010-02-17T06:26:00

Oh...and I also should say...you're misusing the Try/Catch block badly. It's not meant to be used like the old VB6 On Error. If you want to do it that way, .NET still lets you.

A Try/Catch block should be targeted to a single line of code. The majority of code that we write will never throw an exception if we write it properly. By encapsulating everything in a single Try/Catch, you're not getting the information you really need. I'm going to put asterisks in front of all of the lines that don't need to be in a Try/Catch block

VB

Try
* strSQL = "SELECT * FROM User WHERE (Username LIKE ?) AND (Password LIKE ?)"
  Dim dbCmd As New OleDbCommand(strSQL, conn)
* dbCmd.Parameters.AddWithValue("@Username", txtUsername.Text)
* dbCmd.Parameters.AddWithValue("@Password", txtPassword.Text)
  dbReader = dbCmd.ExecuteReader()

  Using dbReader
*   If dbReader.Read() Then
*     Dim strResult1 As String = dbReader.Item("Username")
*     Dim strResult2 As String = dbReader.Item("Password")
*     If chkRememberUsername.Checked = True Then
*       My.Settings.Username = txtUsername.Text
*       My.Settings.Save()
*       My.Settings.Reload()
*     End If
*     Me.Close()
*     mediaSoundPlayer.Stream = My.Resources.tada
*     mediaSoundPlayer.Play()
*     frmLoading.ShowDialog()
*     'frmMain.LogOffToolStripMenuItem.Text = "Log Off"
*     'frmMain.SettingToolStripMenuItem.Enabled = True
*     frmMain.LogOffToolStripMenuItem.Text = "Log Off"
*     Me.Close()
*     frmMain.Show()
*   Else
*     intResult = MessageBox.Show("Invalid Username Or Password", "Login", MessageBoxButtons.RetryCancel, MessageBoxIcon.Error)

*     If intResult = DialogResult.Cancel Then
*       Me.Close()
*     Else
*       intResult = DialogResult.Retry
*       Me.Show()
*     End If
*     frmMain.SettingsToolStripMenuItem.Enabled = False
*     frmMain.LogOffToolStripMenuItem.Text = "Login"
*   End If

* End Using
* conn.Close()
Catch ex As Exception
  MsgBox("System Error", MsgBoxStyle.Critical, "Error in login")
End Try

Christian Graus · Answer 3 · 2010-02-17T11:17:00

Solution 6

What's desperately wrong is that you didn't tell us what the problem is. Did you want us to guess ?

Posted 17-Feb-10 11:17am

Christian Graus

xiroH4ck3r · Answer 4 · 2010-02-18T02:48:00

Solution 7

Im still confuse...
here the link I've upload my project together with the 3rd party software so you can run it..http://www.megaupload.com/?d=3K3MFJI0[^]

Can you help me in coding guys???

Posted 18-Feb-10 2:48am

xiroH4ck3r

OriginalGriff · Answer 5 · 2010-02-15T05:30:00

Solution 1

I assume you are getting the error when the AddWithValue is executed? Try adding the '@' to the "Username" and "Password" in your select statement...

Posted 15-Feb-10 5:30am

OriginalGriff

xiroH4ck3r · Answer 6 · 2010-02-15T17:29:00

you mean here in this line of code?

strSQL = "SELECT * FROM User WHERE (Username LIKE ?) AND (Password LIKE ?)"

So ill make this as

strSQL = "SELECT * FROM User WHERE (@Username LIKE ?) AND (@Password LIKE ?)"

if I remove the try catch the error is in the dbReader = dbCmd.ExecuteReader()

But before that It was working well until I add a column in the database it was originaly only 2 columns in the database the username and password column only until I add new column to that table I begins to give me error messages... This is a big problem because this is my thesis hope someone here could help me with coding my project...