Optimize, propriété – Exemple (VB)

S’applique à : Access 2013, Office 2013

Cet exemple illustre la propriété dynamique Optimize des objets Field. Le champ zip de la table Authors de la base de données Pubs n’est pas indexé. La définition de la propriété Optimize sur True dans le champ zip autorise ADO à créer un index qui améliore les performances de la méthode Find .

 
'BeginOptimizeVB 
Public Sub Main() 
 On Error GoTo ErrorHandler 
 
 'To integrate this code 
 'replace the data source and initial catalog values 
 'in the connection string 
 
 ' 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