System.Data.OleDb.OleDbException was unhandled

[devianleong]

PLease help me. I'm doing a login form with ms access but this line of code having problem "Dim dr As OleDbDataReader = cmd.ExecuteReader"

Below is the source code

Imports System.Data.OleDb

Public Class Form1
    Dim con As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\leong\documents\visual studio 2010\Projects\WindowsApplication4\WindowsApplication4\coursework.mdb")
    Dim cmd As OleDbCommand

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Dim sql = "SELECT Username ,Password FROM AdminUser WHERE Username='" & Logintxt.Text & "' AND Password='" & Passwordtxt.Text & "'"

        cmd = New OleDbCommand(sql, con)
        con.Open()
        Dim dr As OleDbDataReader = cmd.ExecuteReader

        Try
            If dr.Read = False Then
                MessageBox.Show("Authentication failed...")
                Me.Show()
            Else
                MessageBox.Show("Login successfully...")

            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

        con.Close()
    End Sub
End Class

[kvprajapati]

Try to escape the reserved field names and also use parameterized query.

Dim sql = "SELECT [Username],[Password] FROM [AdminUser] WHERE [Username]=@user and [Password]=@pass"
cmd = New OleDbCommand(sql, con)
cmd.Parameters.AddWithValue("@user",Logintxt.Text)
cmd.Parameters.AddWithValue("@pass",Passwordtxt.Text)
con.Open()
Dim dr As OleDbDataReader = cmd.ExecuteReader
...

[devianleong]

Still the same error my friend . Help me ~

[G_Waddell]

Try moving the line con.open() to above cmd = new oledbcommand(sql, con) i.e. have your connection open first
To check that the connection is open before executing the command, you may want to try this:

If Con.State  = ConnectionState.Open Then
    dim dr as OleDBDataReader = cmd.ExecuteReader
    ....
End if

[devianleong]

I had tried this code but still get the same error:

Imports System.Data.OleDb

Public Class Form1
    Dim con As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\leong\documents\visual studio 2010\Projects\WindowsApplication4\WindowsApplication4\coursework.mdb")

    Dim cmd As OleDbCommand

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click


        Dim sql = "SELECT [Username],[Password] FROM [AdminUser] WHERE [Username]=@user and [Password]=@pass"
        con.Open()
        cmd = New OleDbCommand(sql, con)
        cmd.Parameters.AddWithValue("@user", Logintxt.Text)
        cmd.Parameters.AddWithValue("@pass", Passwordtxt.Text)
        If con.State = ConnectionState.Open Then
            Dim dr As OleDbDataReader = cmd.ExecuteReader

            Try
                If dr.Read = False Then
                    MessageBox.Show("Authentication failed...")
                    Me.Show()
                Else
                    MessageBox.Show("Login successfully...")

                End If
            Catch ex As Exception
                MsgBox(ex.Message)
            End Try
        Else
            MsgBox("Error")
        End If
        con.Close()
    End Sub
End Class

[devianleong]

Help~ me pls~

[Ansh8390]

I am having this problem....Please tell me what to do next

[Ansh8390]

Please Help

[Ansh8390]

Please help in this

Imports System.Data.OleDb
Imports System.Data
Public Class Form1
Dim connection As New OleDbConnection(My.Settings.DatabaseConnectionString)
Private Sub PictureBox2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox2.Click
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    If TextBox1.Text = Nothing Or TextBox2.Text = Nothing Then
        MsgBox("Enter Credentials", MsgBoxStyle.Exclamation)
    Else
        If connection.State = ConnectionState.Closed Then
            connection.Open()
        End If
        Dim cmd As New OleDbCommand("select count(*) from login where username=? and lpassword=?", connection)
        cmd.Parameters.AddWithValue("@1", OleDbType.VarChar).Value = TextBox1.Text
        cmd.Parameters.AddWithValue("@2", OleDbType.VarChar).Value = TextBox2.Text
        Dim count = Convert.ToInt32(cmd.ExecuteScalar())
        If (count > 0) Then
            MsgBox("Login Succeed", MsgBoxStyle.Information)
        Else
            MsgBox("Account not found please check credentials", MsgBoxStyle.Critical)
        End If
    End If
End Sub
End Class