如何使用vb.net初始化自动生成的sr.no. [英] how to initialize auto genrated sr.no using vb.net

问题描述

假设我有令牌1到200我想在月末的初始化意味着它将从1开始使用vb.net自动生成

suppose i have token no 1 to 200 i want to initialize at the last of month means it will start automatically generate from 1 using vb.net

推荐答案

逻辑是： NextToken = MAX（令牌）+1其中月份= Current_Month



假设你有一堂课像这样：

The logic is: NextToken = MAX(Token)+1 Where Month = Current_Month

Let's say you have a class like this:

Public Class TokenData
	Private iToken as Integer = 0
	Private dDate as Date
	
	Sub New(ByVal _Token As Integer, ByVal _Date As Date) 
		iToken = _Token
		dDate = _Date
	End Sub
	
	Public Property Token As Integer
		Get
			Return iToken
		End Get
		Set (ByVal _Token As Integer)
			iToken = _Token
		End Set
	End Property

	Public Property mDate As Date
		Get
			Return dDate
		End Get
		Set (ByVal _Date As Date)
			dDate = _Date
		End Set
	End Property
End Class

能够从列表中获取下一个令牌号码（当前月份的TokenData），您需要以这种方式创建linq语句：

To be able to get next Token number from List(of TokenData) for the current month, you need to create linq statement this way:

Sub Main
    'initial Token
    Dim iToken As Integer = 555
    'initial date
    Dim dDate As Date = New Date(2014, 10, 15)

    'declare list of TokenData
    Dim MyData As List(Of TokenData) = New List(Of TokenData)

    'Add initial value
    MyData.Add(New TokenData(iToken, dDate))

    'get next tokens
    Dim i As Integer = 4
    Do While dDate < Date.Today
        dDate = dDate.AddDays(i)
        iToken = MyData.Where(Function(c) c.mDate.Month = dDate.Month And c.mDate.Year=dDate.Year).Select(Function(c) c.Token).DefaultIfEmpty().Max() + 1
        MyData.Add(New TokenData(iToken, dDate))
    Loop

End Sub

结果：

Result:

Token     mDate
555       2014-10-15 00:00:00
556       2014-10-19 00:00:00
557       2014-10-23 00:00:00
558       2014-10-27 00:00:00
559       2014-10-31 00:00:00
1         2014-11-04 00:00:00
2         2014-11-08 00:00:00
3         2014-11-12 00:00:00
4         2014-11-16 00:00:00
5         2014-11-20 00:00:00
6         2014-11-24 00:00:00
7         2014-11-28 00:00:00
1         2014-12-02 00:00:00
2         2014-12-06 00:00:00

这篇关于如何使用vb.net初始化自动生成的sr.no.的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！