Private Sub cmdSearch_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdSearch.Click
 
        'variabeles (objects and strings)
        Dim _root As String = String.Empty
        Dim _Con As OleDb.OleDbConnection = Nothing
        Dim _WhereClause As String = String.Empty
        Dim _Parameter As OleDbParameter = Nothing
        Dim _DataTable As DataTable = Nothing
        Dim _Com As OleDbCommand = Nothing
        Dim _DataAdapter As OleDbDataAdapter
 
        'fill string variabeles
        _root = "yourPathToDatabase\MyDataBase.mdb"
        _Con = New OleDb.OleDbConnection(String.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};User Id=admin;Password=;", _root))
 
        'create objects
        _Com = New OleDbCommand
        _DataTable = New DataTable("Customers")
        _DataAdapter = New OleDbDataAdapter
 
        'check if the searchstring is numeric (if so, the search for an ID has been performed)
        If IsNumeric(txtSearch.Text) Then
            _WhereClause = "ID=@Parameter"
        Else
            _WhereClause = "LCASE(Customer_LastName)=@Parameter"
        End If
 
        Try
            'open the connection to the database
            _Con.Open()
 
            'fill the command with the selectquery and attach a parameter
            With _Com
                .CommandText = String.Format("SELECT * FROM Customers WHERE {0}", _WhereClause)
                .Parameters.AddWithValue("@Parameter", txtSearch.Text.ToLower)
                .Connection = _Con
            End With
 
            'attach command to dataadapter and fill the datatable
            _DataAdapter.SelectCommand = _Com
            _DataAdapter.Fill(_DataTable)
 
        Catch ex As Exception
            'inform the user something has happened
            MessageBox.Show(ex.Message)
        Finally
 
            'if the connection is open, close it
            If _Con.State = ConnectionState.Open Then _Con.Close()
            'dispose and remove objects
            _Con.Dispose()
            _Con = Nothing
            _Com.Dispose()
            _Com = Nothing
        End Try
 
        'attach the datatable to the datagridview
        Me.dgvCustomers.DataSource = _DataTable
 
        'dispose and remove objects
        _DataAdapter.Dispose()
        _DataAdapter = Nothing
        _DataTable.Dispose()
        _DataTable = Nothing
 
    End Sub

cmd = New OleDbCommand("SELECT * from UMP WHERE ", cn)
'to
cmd = New OleDbCommand("SELECT * from UMP WHERE field like " & txtbox.text & "%", cn)