返回月的第一天和最后一天

Public Function Getym(rq As Date) As Date
Dim n As Integer
Dim Getyts As Integer
If ((year(rq) Mod 4 = 0 And year(rq) Mod 100 <> 0) Or year(rq) Mod 400 = 0) Then
n = 1
Else
n = 2
End If

If (n = 1 And Month(rq) = 2) Then
Getyts = 29
ElseIf (n = 2 And Month(rq) = 2) Then
Getyts = 28
End If

Select Case Month(rq)
Case 1, 3, 5, 7, 8, 10, 12
Getyts = 31
Case 4, 6, 9, 11
Getyts = 30
End Select
Getym = CDate(year(rq) & "-" & Month(rq) & "-" & Getyts)
End Function