Imports System.Data.OleDb
Public Class frmLogin
    Private connstring As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\db.mdb"
    Private conn As OleDb.OleDbConnection
    Private dr As OleDb.OleDbDataReader
 
 
    Private Sub frmLogin_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        conn = New OleDbConnection(connstring)
        conn.Open()
    End Sub
 
    Private Sub btnOk_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOk.Click
        Dim cmd As New OleDbCommand("select * from login", conn)
        dr = cmd.ExecuteReader
        dr.Read()
        If dr(0) = txtUser.Text And dr(1) = txtPwd.Text Then
            Form2.Show()
        Else
            txtUser.Clear()
            txtPwd.Clear()
            txtUser.Focus()
        End If
    End Sub
End Class

Dim cmd As New OleDbCommand("select * from login where id= '"+txtUser.Text+"' and pass='"+txtPwd.Text+"'", conn)
        dr = cmd.ExecuteReader
        if(dr.HasRows)
            Form2.Show()
        Else
            txtUser.Clear()
            txtPwd.Clear()
            txtUser.Focus()
        End If