上面的代码已经判断了
Dim yzdh As WinForm.TextBox = e.Form.Controls("dh")'dh是单号控件
Dim di As String = yzdh.Value 'di单号控件中的变量
Dim yzrq As WinForm.DateTimePicker = e.Form.Controls("rq")
Dim d As Date = yzdh.Value
Dim y As Integer = d.Year
Dim m As Integer = d.Month
Dim Days As Integer = Date.DaysInMonth(y,m)
Dim fd As Date = New Date(y,m,1) '获得该月的第一天
Dim ld As Date = New Date(y,m,Days) '获得该月的最后一天
Dim dts As Integer = DataTables("缴费情况").Compute("Count([车牌号码])","[单号] = '" & di & "'")
If e.Form.Controls("rq").value IsNot Nothing And dts = 0 Then
Dim bh As String = "YZ" & "-" & Format(d,"yyyyMM") & "-" '生成编号的前缀
Dim max As String
Dim idx As Integer
Dim flt As String
flt = "[前缀] = 'YZ' And [日期] >= #" & fd & "# And [日期] <= #" & ld & "#"
max = DataTables("缴费情况").Compute("Max(单号)",flt) '取得该月的相同工程代码的最大单据编号
If max > "" Then '如果存在最大单据编号
idx = CInt(max.Substring(10,5)) + 1 '获得最大单据编号的后四位顺序号,并加1
Else
idx = 1 '否则顺序号等于1
End If
di = bh & Format(idx,"00000")
yzdh.Value = di
End If
加好友 
发短信
Post By：2021/3/20 20:19:00 [只看该作者]
此主题相关图片如下：qq图片20210321222936.png