Optimize 属性示例 (VB)

此示例演示 Field 对象的动态 Optimize 属性。 Pubs 数据库中 Authors 表的 zip 字段未编制索引。 将 zip 字段上的 Optimize 属性设置为 True 可授权 ADO 生成索引，从而提高 Find 方法的性能。

'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  

另请参阅

字段对象
Optimize 属性 - 动态 (ADO)