Public Function DaysInMonth_2(d As Date) As Integer
'Из справки Access97
' Returns the number of days in a month
' Requires a date argument, since February can change if it's a leap year
' Lets Access figure it out
'
    If VarType(d) <>  7  Then
        DaysInMonth_2 = Null
    Else
        DaysInMonth_2 = DateSerial(Year(d), Month(d) +  1 ,  1 ) - DateSerial(Year(d), Month(d),  1 )
    End If
End Function

Public Function DaysInMonth(d As Date) As Integer
'
' Возвращает число дней в месяце переданной даты
' Требуется для Февраля функция проверки года LeapYear
'
    If VarType(d) <>  7  Then    'определение какого типа переменая передана для Дат =7
        DaysInMonth = Null
    Else
        Select Case Month(d)
            Case 2
                If LeapYear(Year(d)) Then
                    DaysInMonth = 29
                Else
                    DaysInMonth = 28
                End If
            Case 4, 6, 9, 11
                DaysInMonth = 30
            Case 1, 3, 5, 7, 8, 10, 12
                DaysInMonth = 31
        End Select
    End If
End Function
Public Function LeapYear(YYYY As Integer) As Integer
'
' Leap Year from standard rules
' YYYY:  4 -digit year
'
    LeapYear = YYYY Mod  4  =  0  And (YYYY Mod  100  <>  0  Or YYYY Mod  400  =  0 )
End Function