如何在数据表的行中前后移动？ [英] How can I move forward and backward through rows of a datatable?

问题描述

我有4个按钮（Next，Previous，First，Last）在数据表的行中移动。

按钮First和Last正常工作但其他按钮不正常如果我按下它们，它们会一直指向记录1）。

当我按下最后一个按钮时它会转到最后一个记录，但是当我按下下一个按钮时它会转到第一个记录而不是告诉我没有更多记录。

这是我的表格图片：表格

这是我的代码下面和表格代码：



我尝试过：

  Imports  Microsoft.VisualBasic 
  Imports  System.Data.SqlClient 
  Imports  System.Data 
 
  Partial  类 P3 
 继承 System.Web.UI.Page 
  Dim  ds 作为 新 DataSet 
  Dim  inc  As   Integer  
  Dim  MaxRows  As  整数 
  Dim  tbl  As  DataTable 
 私有  Sub  NavigateRecords（）
 Gidbx.Text = tbl.Rows（inc）.Item（ 0 ）
 Gnamebx.Text = tbl.Rows（inc）.Item（ 1 ）
 结束  Sub  
 
 受保护的  Sub  Page_Load（发件人作为 对象，e 作为 EventArgs）句柄 < span class =code-keyword> Me  .Load 
 
 Response.Write（Session（  slctdGarage））
  Dim  strConnectionString  As  字符串 
  Dim  instsqlconnection  As  SqlConnection 
 strConnectionString =   Integrated Security = SSPI; Initial Catalog = MySetOfGarages; Data Source =。 
 instsqlconnection = 新 SqlConnection（strConnectionString）
 instsqlconnection.Open（）
  Dim  da 作为 新 SqlDataAdapter（  Select * From Garage，instsqlconnection）
 da.Fill（ds，  Grg）
 tbl = ds.Tables （  Grg）
 instsqlconnection.Close（）
 MaxRows = tbl。 Rows.Count 
 inc = -1 
 
 
  End   Sub  
 
 受保护的  Sub  Nextrec_Click（sender 作为 对象，e 作为 EventArgs）句柄 Nextrec.Click 
 如果 inc<> MaxRows  -   1  然后 
 inc = inc +  1  
 NavigateRecords（）
 其他 
 Response.Write（  没有更多行）
 结束 如果 
 
 结束  Sub  
 
 受保护的  Sub  Previousrec_Click（发件人 As  对象，e 作为 EventArgs）句柄 Previousrec。点击
 如果 inc>  0  然后 
 inc = inc  -   1  
 NavigateRecords（）
  ElseIf  inc = -1 然后 
 Response.Write（ 还没有记录）
  ElseIf  inc =  0  然后 
 Response.Write（< span class =code-string>  First Record）
 
 结束 如果 
 
 结束  Sub  
 
 受保护的  Sub  Lastrec_Click（发件人< span class =code-keyword> As  对象，e  As  EventArgs）句柄 Lastrec.Click 
 < span class =code-keyword>如果 inc<> MaxRows  -   1  然后 
 inc = MaxRows  -   1  
 NavigateRecords（）
 结束 如果 
 
 结束  Sub  
 
 受保护的  Sub  Firstrec_Click（发件人作为 对象，e  As  EventArgs）句柄 Firstrec.Click 
 如果 inc<>  0  然后 
 inc =  0  
 NavigateRecords（）
 结束 如果 
 
 结束  Sub  
 结束 < span class =code-keyword> Class  

 <％@     Page    语言  =  VB    AutoEventWireup   =  false    CodeFile   =  P3.aspx.vb   继承  =  P3   ％>  
 
 
 <  表格    id   =  form1    runat   =  server >  
 <   p  >  
 id Garage 
 <   asp：TextBox     ID   =   Gidbx    runat   = 服务器 >  <   / asp：TextBox  >  
 <   / p  >  
 <   p  >  
 GarageName 
 <   asp：TextBox     ID   =  Gnamebx    runat   = 服务器 >  <   / asp：TextBox  >  
 
 <   asp：按钮    ID   =  Firstrec    runat   =  server   文字  = <<    /  >  
 
 <   asp：按钮    ID  < span class =code-keyword> =  Previousrec    runat   =  server   文字  = <     /  >  
 
 <   asp：按钮    ID   =  Ne xtrec    runat   =  server   文本  = >    /  >  
 
 <   asp：按钮    ID   =  Lastrec    runat   =  server   文字  = >>    /  >  
 <   / p  >  
 <   p  >  
 
 <   asp：按钮    ID   =  Button1    runat   =  server   文本  = 添加记录    /  >  
 
 <   asp：按钮    ID   =  Button2    runat   =  server   文字  = 更新Rec    /  >  
 
 <   asp：Button     ID   =  Button3    runat   =  server   文本  = 删除Rec     /  >  
 <   / p  >  
 <   / form  >  

解决方案

在这个类似的问题上参考我的常见答案，但它是用C＃编写的，试着理解逻辑和在你的应用程序中实现



第一个下一个上一个按钮的代码和页面窗口中的显示数据C＃application [ ^ ]





使用它将c＃转换为VB CodeTranslator：从c＃到VB的代码翻译 [ ^ ]

I have 4 buttons (Next,Previous,First,Last) which moves through the rows of a datatable.
The buttons First and Last are working correctly but the other buttons are not(nothing happens if i press them,they keep pointing to record 1).
When i press the Last button it goes to the last record,but when i press the next button it takes me to the first record instead of telling me "No more Records".
This is a pic of my form: Form
This is my code Below and the form code:

What I have tried:

Imports Microsoft.VisualBasic
Imports System.Data.SqlClient
Imports System.Data

Partial Class P3
    Inherits System.Web.UI.Page
    Dim ds As New DataSet
    Dim inc As Integer
    Dim MaxRows As Integer
    Dim tbl As DataTable
    Private Sub NavigateRecords()
        Gidbx.Text = tbl.Rows(inc).Item(0)
        Gnamebx.Text = tbl.Rows(inc).Item(1)
    End Sub

    Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
       
        Response.Write(Session("slctdGarage"))
        Dim strConnectionString As String
        Dim instsqlconnection As SqlConnection
        strConnectionString = "Integrated Security=SSPI;Initial Catalog=MySetOfGarages;Data Source=."
        instsqlconnection = New SqlConnection(strConnectionString)
        instsqlconnection.Open()
        Dim da As New SqlDataAdapter("Select * From Garage", instsqlconnection)
        da.Fill(ds, "Grg")
        tbl = ds.Tables("Grg")
        instsqlconnection.Close()
        MaxRows = tbl.Rows.Count
        inc = -1

      
    End Sub

    Protected Sub Nextrec_Click(sender As Object, e As EventArgs) Handles Nextrec.Click
        If inc <> MaxRows - 1 Then
            inc = inc + 1
            NavigateRecords()
        Else
            Response.Write("No More Rows")
        End If

    End Sub

    Protected Sub Previousrec_Click(sender As Object, e As EventArgs) Handles Previousrec.Click
        If inc > 0 Then
            inc = inc - 1
            NavigateRecords()
        ElseIf inc = -1 Then
            Response.Write("No Records Yet")
        ElseIf inc = 0 Then
            Response.Write("First Record")

        End If

    End Sub

    Protected Sub Lastrec_Click(sender As Object, e As EventArgs) Handles Lastrec.Click
        If inc <> MaxRows - 1 Then
            inc = MaxRows - 1
            NavigateRecords()
        End If

    End Sub

    Protected Sub Firstrec_Click(sender As Object, e As EventArgs) Handles Firstrec.Click
        If inc <> 0 Then
            inc = 0
            NavigateRecords()
        End If

    End Sub
End Class

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="P3.aspx.vb" Inherits="P3" %>


<form id="form1" runat="server">
    <p>
         id Garage      
        <asp:TextBox ID="Gidbx" runat="server"></asp:TextBox>
         </p>
    <p>
         GarageName 
        <asp:TextBox ID="Gnamebx" runat="server"></asp:TextBox>
            
        <asp:Button ID="Firstrec" runat="server" Text="<<" />
 
        <asp:Button ID="Previousrec" runat="server" Text="<" />
 
        <asp:Button ID="Nextrec" runat="server" Text=">" />
 
        <asp:Button ID="Lastrec" runat="server" Text=">>" />
    </p>
    <p>
                         
        <asp:Button ID="Button1" runat="server" Text="Add Record" />
               
        <asp:Button ID="Button2" runat="server" Text="Update Rec" />
        
        <asp:Button ID="Button3" runat="server" Text="Delete Rec" />
    </p>
</form>

解决方案

refer my prev answer on this similar question, but it was written on C#, try to understand the logic and implement in your app

Code for first next last previous button and display data in page windows C# application[^]


use this for converting the c# to VB CodeTranslator: Code Translation From c# to VB [^]

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