Optimize 屬性範例 (VB)
此範例示範 Field 物件的動態 Optimize 屬性。 Pubs 資料庫中 Authors 資料表的 zip 欄位不會編制索引。 在 zip 欄位上將 Optimize 屬性設定為 True 會授權 ADO 建置索引，以改善 Find 方法的效能。
'BeginOptimizeVB
Public Sub Main()
On Error GoTo ErrorHandler
'To integrate this code
'replace the data source and initial catalog values
'in the connection string.
' Declare the recordset and connection variables.
Dim Cnxn As ADODB.Connection
Dim rstAuthors As ADODB.Recordset
Dim strCnxn As String
Dim strSQLAuthors As String
' Open connection.
strCnxn = "Provider='sqloledb';Data Source='MySqlServer';" & _
"Initial Catalog='Pubs';Integrated Security='SSPI';"
Set Cnxn = New ADODB.Connection
Cnxn.Open strCnxn
' open recordset client-side to enable index creation.
Set rstAuthors = New ADODB.Recordset
rstAuthors.CursorLocation = adUseClient
strSQLAuthors = "SELECT * FROM Authors"
rstAuthors.Open strSQLAuthors, Cnxn, adOpenStatic, adLockReadOnly, adCmdText
' Create the index.
rstAuthors!zip.Properties("Optimize") = True
' Find Akiko Yokomoto
rstAuthors.Find "zip = '94595'"
' Show results.
Debug.Print rstAuthors!au_fname & " " & rstAuthors!au_lname & " " & _
rstAuthors!address & " " & rstAuthors!city & " " & rstAuthors!State
rstAuthors!zip.Properties("Optimize") = False 'Delete the index.
' Clean up.
rstAuthors.Close
Cnxn.Close
Set rstAuthors = Nothing
Set Cnxn = Nothing
Exit Sub
ErrorHandler:
' clean up
If Not rstAuthors Is Nothing Then
If rstAuthors.State = adStateOpen Then rstAuthors.Close
End If
Set rstAuthors = 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
'EndOptimizeVB