CacheSize 属性示例 (VB)

适用于：Access 2013、Office 2013

此示例使用 CacheSize 属性显示在使用和不使用 30 条记录大小的缓存的情况下执行一个操作时的性能差异。

 
'BeginCacheSizeVB 
 
 'To integrate this code 
 'replace the data source and initial catalog values 
 'in the connection string 
 
Public Sub Main() 
 On Error GoTo ErrorHandler 
 
 'recordset and connection variables 
 Dim rstRoySched As ADODB.Recordset 
 Dim strSQLSched As String 
 Dim strCnxn As String 
 'record variables 
 Dim sngStart As Single 
 Dim sngEnd As Single 
 Dim sngNoCache As Single 
 Dim sngCache As Single 
 Dim intLoop As Integer 
 Dim strTemp As String 
 
 ' Open the connection 
 strCnxn = "Provider='sqloledb';Data Source='MySqlServer';" & _ 
 "Initial Catalog='Pubs';Integrated Security='SSPI';" 
 
 ' Open the RoySched Table 
 Set rstRoySched = New ADODB.Recordset 
 strSQLSched = "roysched" 
 rstRoySched.Open strSQLSched, strCnxn, , , adCmdTable 
 
 ' Enumerate the Recordset object twice and 
 ' record the elapsed time 
 sngStart = Timer 
 
 For intLoop = 1 To 2 
 rstRoySched.MoveFirst 
 
 If Not rstRoySched.EOF Then 
 ' Execute a simple operation for the 
 ' performance test 
 Do 
 strTemp = rstRoySched!title_id 
 rstRoySched.MoveNext 
 Loop Until rstRoySched.EOF 
 End If 
 Next intLoop 
 
 sngEnd = Timer 
 sngNoCache = sngEnd - sngStart 
 
 ' Cache records in groups of 30 records. 
 rstRoySched.MoveFirst 
 rstRoySched.CacheSize = 30 
 sngStart = Timer 
 
 ' Enumerate the Recordset object twice and record 
 ' the elapsed time 
 For intLoop = 1 To 2 
 rstRoySched.MoveFirst 
 Do While Not rstRoySched.EOF 
 ' Execute a simple operation for the 
 ' performance test 
 strTemp = rstRoySched!title_id 
 rstRoySched.MoveNext 
 Loop 
 Next intLoop 
 
 sngEnd = Timer 
 sngCache = sngEnd - sngStart 
 
 ' Display performance results. 
 MsgBox "Caching Performance Results:" & vbCr & _ 
 " No cache: " & Format(sngNoCache, "##0.000") & " seconds" & vbCr & _ 
 " 30-record cache: " & Format(sngCache, "##0.000") & " seconds" 
 
 ' clean up 
 rstRoySched.Close 
 Set rstRoySched = Nothing 
 Exit Sub 
 
ErrorHandler: 
 ' clean up 
 If Not rstRoySched Is Nothing Then 
 If rstRoySched.State = adStateOpen Then rstRoySched.Close 
 End If 
 Set rstRoySched = Nothing 
 
 If Err <> 0 Then 
 MsgBox Err.Source & "-->" & Err.Description, , "Error" 
 End If 
End Sub 
'EndCacheSizeVB