Hi everyone Could someone please help me, I need to loop through all the records in a column in my access database, Currently my program only views the first record in the column and does not go any further, I tried a While loop but I get a NullException error and it says there is no data in my column, her is my code thus far.

Imports System.Data.OleDb
Imports System.Security
Imports System.Security.Principal.WindowsIdentity
Public Class form_Login
    Dim dbReader As OleDbDataReader
    Dim dbConnect As New OleDb.OleDbConnection
    Dim dbCommand As OleDbCommand
    Dim Line As String = Environment.NewLine
    Dim ValidUser As Boolean
    Dim CurrentUser As String = GetCurrent.Name
    Private Sub btnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLogin.Click
        MessageBox.Show(CurrentUser)
        dbReader = dbCommand.ExecuteReader
        dbReader.Read()
        If dbReader("Abnum") = CurrentUser Then
            ValidUser = True
        End If
        MessageBox.Show(dbReader("Abnum"))
        If ValidUser = True Then
            Dim mainForm As New form_MainMenu
            btnLogin.Enabled = False
            mainForm.Show()
            Me.Hide()
        Else
            lblMessage.Text = "You are not a Registered User for this Application"
        End If
    End Sub
    Private Sub form_Login_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Try
            dbConnect.ConnectionString = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source = C:\Database\WorkWatchMain.mdb"
            dbConnect.Open()
            dbCommand = New OleDbCommand("SELECT * FROM Table_Login", dbConnect)
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub
End Class

Abnum is my column name, if you were wondering, and don't worry about the connection, that works perfectly.

O.K don't worry got it to work on my own. Here is the final code, I'm not going to get into the details because the variables have been named in such a way that the code should be self explanatory.

Imports System.Data.OleDb
Imports System.Security
Imports System.Security.Principal.WindowsIdentity
Public Class form_Login
    Dim dbReader As OleDbDataReader
    Dim dbConnect As New OleDb.OleDbConnection
    Dim dbCommand As OleDbCommand
    Dim Line As String = Environment.NewLine
    Dim ValidUser As Boolean = False
    Dim CurrentUser As String = GetCurrent.Name
    Dim dbDataSet As DataSet = New DataSet("Table_Login")
    Dim dbAdapter As OleDb.OleDbDataAdapter
    Dim intDbRecords As Integer
    Dim dbRow As DataRow
    Dim dbTable As DataTable
    Dim sql As String
    Private Sub btnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLogin.Click
        dbReader = dbCommand.ExecuteReader
        dbReader.Read()
        dbTable = dbDataSet.Tables("Table_Login")
        For Each dbRow In dbTable.Rows
            If dbRow("Abnum").ToString = CurrentUser.ToString Then
                ValidUser = True
                Exit For
            End If
        Next
        If ValidUser = True Then
            If dbRow("Tiepe").ToString = "Manager" Then
                Dim mainForm As New form_MainMenu
                btnLogin.Enabled = False
                mainForm.Show()
                Me.Hide()
            ElseIf dbRow("Tiepe").ToString = "Agent" Then
                Dim agentForm As New form_AgentWork
                btnLogin.Enabled = False
                agentForm.Show()
                Me.Hide()
            ElseIf dbRow("Tiepe").ToString = "Teller" Then
                Dim tellerForm As New form_TellerWork
                btnLogin.Enabled = False
                tellerForm.Show()
                Me.Hide()
            ElseIf dbRow("Tiepe").ToString = "Mandate Holder" Then
                Dim mainForm As New form_MainMenu
                btnLogin.Enabled = False
                mainForm.Show()
                Me.Hide()
            End If
        Else
            lblMessage.Text = "You are not a Registered User for this Application" + Line + "Contact Your Manager or Mandate Holder" + Line + "Exit this Application now"
            PicBoxError.Visible = True 
        End If
    End Sub
    Private Sub form_Login_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Try
            dbConnect.ConnectionString = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source = C:\Database\WorkWatchMain.mdb"
            dbConnect.Open()
            dbCommand = New OleDbCommand("SELECT * FROM Table_Login", dbConnect)
            sql = "SELECT * FROM Table_Login"
            dbAdapter = New OleDb.OleDbDataAdapter(sql, dbConnect.ConnectionString)
            dbAdapter.Fill(dbDataSet, "Table_Login")
        Catch ex As Exception
            MessageBox.Show(ex.Message + Line + "Main Database Not Found" + Line + "Check form_AccessMaintenance source code" + Line + "Database Path", "Critical Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
        End Try
    End Sub
End Class

This code was written to check usernames in a database and give access to diffrent forms in the application depending on their job type.

Hope this helps.

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