MoveFirst、MoveLast、MoveNext 和 MovePrevious 方法范例
内容
MoveFirst、MoveLast、MoveNext 和 MovePrevious 方法范例
该范例使用 MoveFirst、MoveLast、MoveNext 以及 MovePrevious 方法，按照所提供的命令移动 Recordset 的记录指针。运行该过程需要 MoveAny 过程。
Public Sub MoveFirstX()
Dim rstAuthors As ADODB.Recordset
Dim strCnn As String
Dim strMessage As String
Dim intCommand As Integer
' 打开 Authors 表的记录集。
strCnn = "Provider=sqloledb;" & _
"Data Source=srv;Initial Catalog=pubs;User Id=sa;Password=; "
Set rstAuthors = New ADODB.Recordset
rstAuthors.CursorType = adOpenStatic
' 使用客户端游标激活 AbsolutePosition 属性。
rstAuthors.CursorLocation = adUseClient
rstAuthors.Open "authors", strCnn, , , adCmdTable
' 显示当前记录信息并获得用户的方法选择。
Do While True
strMessage = "Name: " & rstAuthors!au_fName & " " & _
rstAuthors!au_lName & vbCr & "Record " & _
rstAuthors.AbsolutePosition & " of " & _
rstAuthors.RecordCount & vbCr & vbCr & _
"[1 - MoveFirst, 2 - MoveLast, " & vbCr & _
"3 - MoveNext, 4 - MovePrevious]"
intCommand = Val(Left(InputBox(strMessage), 1))
If intCommand < 1 Or intCommand > 4 Then Exit Do
' 根据用户输入调用方法。
MoveAny intCommand, rstAuthors
Loop
rstAuthors.Close
End Sub
Public Sub MoveAny(intChoice As Integer, _
rstTemp As Recordset)
' 使用指定方法捕获 BOF 和 EOF。
Select Case intChoice
Case 1
rstTemp.MoveFirst
Case 2
rstTemp.MoveLast
Case 3
rstTemp.MoveNext
If rstTemp.EOF Then
MsgBox "Already at end of recordset!"
rstTemp.MoveLast
End If
Case 4
rstTemp.MovePrevious
If rstTemp.BOF Then
MsgBox "Already at beginning of recordset!"
rstTemp.MoveFirst
End If
End Select
End Sub
VBScript 版本
下面是使用 VBScript 编写、并用于 Active Server Page (ASP) 的相同范例。如需查看该完整功能范例，请使用与 IIS 一同安装并位于 C:\InetPub\ASPSamp\AdvWorks 的数据源 AdvWorks.mdb，来创建名为 AdvWorks 的系统“数据源名称”(DSN)。这是 Microsoft Access 数据库文件。请使用查找命令定位文件 Adovbs.inc，并将其放入计划使用的目录中。请将以下代码剪切并粘贴到记事本或其他文本编辑器中，另存为“MoveOne.asp”。这样，便可在任何客户端浏览器中查看结果。
可尝试在记录集的上限和下限之外移动以查看错误处理的运作。
<!-- #Include file="ADOVBS.INC" -->
<% Language = VBScript %>
<HTML><HEAD>
<TITLE>ADO MoveNext MovePrevious MoveLast MoveFirst Methods</TITLE></HEAD>
<BODY>
<FONT FACE="MS SANS SERIF" SIZE=2>
<Center>
<H3>ADO Methods<BR>MoveNext MovePrevious MoveLast MoveFirst</H3>
<!-- 在服务器上创建 Connection 和 Recordset 对象 -->
<%
' 创建并打开 Connection 对象。
Set OBJdbConnection = Server.CreateObject("ADODB.Connection")
OBJdbConnection.Open "AdvWorks"
' 创建并打开 Recordset 对象。
Set RsCustomerList = Server.CreateObject("ADODB.Recordset")
RsCustomerList.ActiveConnection = OBJdbConnection
RsCustomerList.CursorType = adOpenKeyset
RsCustomerList.LockType = adLockOptimistic
RsCustomerList.Source = "Customers"
RsCustomerList.Open
' 检查 Request.Form 集合以查看所记录的任何移动。
If Not IsEmpty(Request.Form("MoveAmount")) Then
' 跟踪该会话的移动数目和方向。
Session("Moves") = Session("Moves") + Request.Form("MoveAmount")
Clicks = Session("Moves")
' 移动到上一个已知位置。
RsCustomerList.Move CInt(Clicks)
' 检查移动为 + 还是 - 并进行错误检查。
If CInt(Request.Form("MoveAmount")) = 1 Then
If RsCustomerList.EOF Then
Session("Moves") = RsCustomerList.RecordCount
RsCustomerList.MoveLast
End If
RsCustomerList.MoveNext
End If
If Request.Form("MoveAmount") < 1 Then
RsCustomerList.MovePrevious
End If
' 检查有无单击 First Record 或 Last Record 命令按钮。
If Request.Form("MoveLast") = 3 Then
RsCustomerList.MoveLast
Session("Moves") = RsCustomerList.RecordCount
End If
If Request.Form("MoveFirst") = 2 Then
RsCustomerList.MoveFirst
Session("Moves") = 1
End If
End If
' 对 Move Button 单击组合进行错误检查。
If RsCustomerList.EOF Then
Session("Moves") = RsCustomerList.RecordCount
RsCustomerList.MoveLast
Response.Write "This is the Last Record"
End If
If RsCustomerList.BOF Then
Session("Moves") = 1
RsCustomerList.MoveFirst
Response.Write "This is the First Record"
End If
%>
<H3>Current Record Number is <BR>
<!-- 显示当前记录数目和记录集大小 -->
<% If IsEmpty(Session("Moves")) Then
Session("Moves") = 1
End If
%>
<%Response.Write(Session("Moves") )%> of <%=RsCustomerList.RecordCount%></H3>
<HR>
<Center><TABLE COLSPAN=8 CELLPADDING=5 BORDER=0>
<!-- Customer 表的 BEGIN 列标头行 -->
<TR><TD ALIGN=CENTER BGCOLOR="#008080">
<FONT STYLE="ARIAL NARROW" COLOR="#ffffff" SIZE=1>Company Name</FONT>
</TD>
<TD ALIGN=CENTER BGCOLOR="#008080">
<FONT STYLE="ARIAL NARROW" COLOR="#ffffff" SIZE=1>Contact Name</FONT>
</TD>
<TD ALIGN=CENTER WIDTH=150 BGCOLOR="#008080">
<FONT STYLE="ARIAL NARROW" COLOR="#ffffff" SIZE=1>Phone Number</FONT>
</TD>
<TD ALIGN=CENTER BGCOLOR="#008080">
<FONT STYLE="ARIAL NARROW" COLOR="#ffffff" SIZE=1>City</FONT>
</TD>
<TD ALIGN=CENTER BGCOLOR="#008080">
<FONT STYLE="ARIAL NARROW" COLOR="#ffffff" SIZE=1>State/Province</FONT>
</TD></TR>
<!-- 显示 Customer 表的 ADO 数据 -->
<TR>
<TD BGCOLOR="f7efde" ALIGN=CENTER>
<FONT STYLE="ARIAL NARROW" SIZE=1>
<%= RSCustomerList("CompanyName")%>
</FONT></TD>
<TD BGCOLOR="f7efde" ALIGN=CENTER>
<FONT STYLE="ARIAL NARROW" SIZE=1>
<%= RScustomerList("ContactLastName") & ", " %>
<%= RScustomerList("ContactFirstName") %>
</FONT></TD>
<TD BGCOLOR="f7efde" ALIGN=CENTER>
<FONT STYLE="ARIAL NARROW" SIZE=1>
<%= RScustomerList("PhoneNumber")%>
</FONT></TD>
<TD BGCOLOR="f7efde" ALIGN=CENTER>
<FONT STYLE="ARIAL NARROW" SIZE=1>
<%= RScustomerList("City")%>
</FONT></TD>
<TD BGCOLOR="f7efde" ALIGN=CENTER>
<FONT STYLE="ARIAL NARROW" SIZE=1>
<%= RScustomerList("StateOrProvince")%>
</FONT></TD>
</TR> </Table></FONT>
<HR>
<Input Type = Button Name = cmdDown Value = "< ">
<Input Type = Button Name = cmdUp Value = " >">
<BR>
<Input Type = Button Name = cmdFirst Value = "First Record">
<Input Type = Button Name = cmdLast Value = "Last Record">
<H5>Click Direction Arrows to Use MovePrevious or MoveNext
<BR> </H5>
<!-- 使用隐含窗体字段将值发送到服务器 -->
<Form Method = Post Action="MoveOne.asp" Name=Form>
<Input Type="Hidden" Size="4" Name="MoveAmount" Value = 0>
<Input Type="Hidden" Size="4" Name="MoveLast" Value = 0>
<Input Type="Hidden" Size="4" Name="MoveFirst" Value = 0>
</Form></BODY>
<Script Language = "VBScript">
Sub cmdDown_OnClick
' 在 Input Boxes 窗体和 Submit 窗体中设置值。
Document.Form.MoveAmount.Value = -1
Document.Form.Submit
End Sub
Sub cmdUp_OnClick
Document.Form.MoveAmount.Value = 1
Document.Form.Submit
End Sub
Sub cmdFirst_OnClick
Document.Form.MoveFirst.Value = 2
Document.Form.Submit
End Sub
Sub cmdLast_OnClick
Document.Form.MoveLast.Value = 3
Document.Form.Submit
End Sub
</Script></HTML>