悟靜 2012-09-22

展開全文

要SQL查詢語句前，就須把上一篇和下一篇的文章ID找出來，下面的SQL語句有些字段已經(jīng)省略。

View Code

SELECT [ArticleId],[Subject],
    (SELECT MAX([ArticleId]) FROM [dbo].[Article] AS a1 WHERE a1.[ArticleId] < a.[ArticleId]) AS [PrevArticleId],
    (SELECT MIN([ArticleId]) FROM [dbo].[Article] AS a1 WHERE a1.[ArticleId] > a.[ArticleId]) AS [NextArticleId]
    FROM [dbo].[Article] AS a

執(zhí)行結果：

數(shù)據(jù)庫方面完成了，接下來在asp.net實現(xiàn)，可以首先創(chuàng)建一個用戶控件：

ArticleNavigation.ascx：

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<%@ Control Language="VB" AutoEventWireup="false" CodeFile="ArticleNavigation.ascx.vb" Inherits="SiteControls_ArticleNavigation" %>
上一篇：<asp:HyperLink ID="HyperLinkPrev" runat="server" Target="_blank"></asp:HyperLink> <br />
下一篇：<asp:HyperLink ID="HyperLinkNext" runat="server" Target="_blank"></asp:HyperLink>

ArticleNavigation.ascx.vb：

View Code

Imports System.Data
Imports Insus.NET

Partial Class SiteControls_ArticleNavigation
    Inherits System.Web.UI.UserControl
    Dim objArticle As New Article()

    Private _PrevArticleId As String
    Private _NextArticleId As String

    Public WriteOnly Property PrevArticleId As String
        Set(value As String)
            _PrevArticleId = value
        End Set
    End Property

    Public WriteOnly Property NextArticleId As String
        Set(value As String)
            _NextArticleId = value
        End Set
    End Property

    Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
        Data_Binding()
    End Sub

    Private Sub Data_Binding()
        If String.IsNullOrEmpty(_PrevArticleId) Then
            Me.HyperLinkPrev.Text = "無"
        Else
            Dim objPrevDataRow As DataRow = objArticle.GetArticleByPrimaryKey(_PrevArticleId).Rows(0)
            Me.HyperLinkPrev.Text = objPrevDataRow("Subject")
            Me.HyperLinkPrev.NavigateUrl = "~/ArticleView.aspx?ID=" & _PrevArticleId
        End If

        If String.IsNullOrEmpty(_NextArticleId) Then
            Me.HyperLinkNext.Text = "無"
        Else
            Dim objNextDataRow As DataRow = objArticle.GetArticleByPrimaryKey(_NextArticleId).Rows(0)
            Me.HyperLinkNext.Text = objNextDataRow("Subject")
            Me.HyperLinkNext.NavigateUrl = "~/ArticleView.aspx?ID=" & _NextArticleId
        End If
    End Sub

End Class

在文章瀏覽的aspx中，用戶控控件需要傳入前一篇的文章ID和下一篇的文章ID，下面的PrevArticleId和NextArticleId兩個都是用戶控件的public的屬性。

View Code

<uc1:ArticleNavigation ID="ArticleNavigation1" runat="server" PrevArticleId='<%# Eval("PrevArticleId")%>'
NextArticleId='<%# Eval("NextArticleId")%>' />