Filter 和 RecordCount 属性示例 (VB)Filter and RecordCount properties example (VB)

09/18/2015

本文内容

适用于：Access 2013、Office 2013Applies to: Access 2013, Office 2013

本示例打开 Pubs 数据库 Publishers(发行商)表上的一个 Recordset。This example open a Recordset on the Publishers table in the Pubs database. 然后使用 Filter 属性将可见的记录数限制为发行商属于特定国家/地区的记录。It then uses the Filter property to limit the number of visible records to those publishers in a particular country/region. RecordCount 属性用于显示筛选和未筛选的记录集之间的差值。The RecordCount property is used to show the difference between the filtered and unfiltered recordsets.

'BeginFilterVB

'To integrate this code

'replace the data source and initial catalog values

'in the connection string

Public Sub Main()

On Error GoTo ErrorHandler

' recordset variables

Dim rstPublishers As ADODB.Recordset

Dim Cnxn As ADODB.Connection

Dim strCnxn As String

Dim SQLPublishers As String

' criteria variables

Dim intPublisherCount As Integer

Dim strCountry As String

Dim strMessage As String

' open connection

Set Cnxn = New ADODB.Connection

strCnxn = "Provider='sqloledb';Data Source='MySqlServer';" & _

"Initial Catalog='Pubs';Integrated Security='SSPI';"

Cnxn.Open strCnxn

' open recordset with data from Publishers table

Set rstPublishers = New ADODB.Recordset

SQLPublishers = "publishers"

rstPublishers.Open SQLPublishers, strCnxn, adOpenStatic, , adCmdTable

intPublisherCount = rstPublishers.RecordCount

' get user input

strCountry = Trim(InputBox("Enter a country to filter on (e.g. USA):"))

If strCountry <> "" Then

' open a filtered Recordset object

rstPublishers.Filter = "Country ='" & strCountry & "'"

If rstPublishers.RecordCount = 0 Then

MsgBox "No publishers from that country."

Else

' print number of records for the original recordset

' and the filtered recordset

strMessage = "Orders in original recordset: " & _

vbCr & intPublisherCount & vbCr & _

"Orders in filtered recordset (Country = '" & _

strCountry & "'): " & vbCr & _

rstPublishers.RecordCount

MsgBox strMessage

End If

End If

' clean up

rstPublishers.Close

Cnxn.Close

Set rstPublishers = Nothing

Set Cnxn = Nothing

Exit Sub

ErrorHandler:

' clean up

If Not rstPublishers Is Nothing Then

If rstPublishers.State = adStateOpen Then rstPublishers.Close

End If

Set rstPublishers = Nothing

If Not Cnxn Is Nothing Then

If Cnxn.State = adStateOpen Then Cnxn.Close

End If

Set Cnxn = Nothing

If Err <> 0 Then

MsgBox Err.Source & "-->" & Err.Description, , "Error"

End If

End Sub

'EndFilterVB

备注

[!注释] 如果知道要选择的数据，通过这种方式打开 Recordset 通过比使用 SQL 语句效率更高。本示例演示如何仅创建一个 Recordset 并获取特定国家/地区的记录。When you know the data you want to select, it's usually more efficient to open a Recordset with an SQL statement. This example shows how you can create just one Recordset and obtain records from a particular country/region.

'BeginFilter2VB

'To integrate this code

'replace the data source and initial catalog values

'in the connection string

Public Sub Main()

On Error GoTo ErrorHandler

Dim rstPublishers As ADODB.Recordset

Dim Cnxn As ADODB.Connection

Dim strSQLPublishers As String

Dim strCnxn As String

' open connection

Set Cnxn = New ADODB.Connection

strCnxn = "Provider='sqloledb';Data Source='MySqlServer';" & _

"Initial Catalog='Pubs';Integrated Security='SSPI';"

Cnxn.Open strCnxn

' open recordset with criteria from Publishers table

Set rstPublishers = New ADODB.Recordset

strSQLPublishers = "SELECT * FROM publishers WHERE Country = 'USA'"

rstPublishers.Open strSQLPublishers, Cnxn, adOpenStatic, adLockReadOnly, adCmdText

' print recordset

rstPublishers.MoveFirst

Do While Not rstPublishers.EOF

Debug.Print rstPublishers!pub_name & ", " & rstPublishers!country

rstPublishers.MoveNext

Loop

' clean up

rstPublishers.Close

Cnxn.Close

Set rstPublishers = Nothing

Set Cnxn = Nothing

Exit Sub

ErrorHandler:

' clean up

If Not rstPublishers Is Nothing Then

If rstPublishers.State = adStateOpen Then rstPublishers.Close

End If

Set rstPublishers = Nothing

If Not Cnxn Is Nothing Then

If Cnxn.State = adStateOpen Then Cnxn.Close

End If

Set Cnxn = Nothing

If Err <> 0 Then

MsgBox Err.Source & "-->" & Err.Description, , "Error"

End If

End Sub

'EndFilter2VB