Optimize, propriété – Exemple (VJ++)

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 .

 
// BeginOptimizeJ 
import com.ms.wfc.data.*; 
import java.io.* ; 
 
public class OptimizeX 
{ 
 // The main entry point for the application. 
 
 public static void main (String[] args) 
 { 
 OptimizeX(); 
 System.exit(0); 
 } 
 
 // OptimizeX function 
 
 static void OptimizeX() 
 { 
 
 // Define ADO Objects. 
 Recordset rstAuthors = null; 
 
 // Declarations. 
 BufferedReader in = 
 new BufferedReader (new InputStreamReader(System.in)); 
 String strCnn = "Provider='sqloledb';Data Source='MySqlServer';" 
 + "Initial Catalog='Pubs';Integrated Security='SSPI';"; 
 
 try 
 { 
 rstAuthors = new Recordset(); 
 rstAuthors.setCursorLocation(AdoEnums.CursorLocation.CLIENT); 
 // Enable index creation. 
 rstAuthors.open("SELECT * FROM Authors", 
 strCnn, 
 AdoEnums.CursorType.STATIC, 
 AdoEnums.LockType.READONLY, 
 AdoEnums.CommandType.TEXT); 
 rstAuthors.getField("zip").getProperties(). 
 getItem("Optimize").setBoolean(true); // Create the index. 
 rstAuthors.find("zip = '94595'"); // Find Akiko Yokomoto. 
 System.out.println(rstAuthors.getField("au_fname").getString() + 
 " " + rstAuthors.getField("au_lname").getString() + " " + 
 rstAuthors.getField("address").getString() + " " + 
 rstAuthors.getField("city").getString() + " " + 
 rstAuthors.getField("state").getString() + " "); 
 rstAuthors.getField("zip").getProperties(). 
 getItem("Optimize").setBoolean(false); // Delete the index. 
 
 System.out.println("\nPress <Enter> to continue.."); 
 in.readLine(); 
 } 
 catch( AdoException ae ) 
 { 
 // Notify user of any errors that result from ADO. 
 
 // As passing a Recordset, check for null pointer first. 
 if (rstAuthors != null) 
 { 
 PrintProviderError(rstAuthors.getActiveConnection()); 
 } 
 else 
 { 
 System.out.println("Exception: " + ae.getMessage()); 
 } 
 } 
 
 // System read requires this catch. 
 catch( java.io.IOException je) 
 { 
 PrintIOError(je); 
 } 
 
 finally 
 { 
 // Cleanup objects before exit. 
 if (rstAuthors != null) 
 if (rstAuthors.getState() == 1) 
 rstAuthors.close(); 
 } 
 } 
 
 // PrintProviderError Function 
 
 static void PrintProviderError( Connection Cnn1 ) 
 { 
 // Print Provider errors from Connection object. 
 // ErrItem is an item object in the Connections Errors collection. 
 com.ms.wfc.data.Error ErrItem = null; 
 long nCount = 0; 
 int i = 0; 
 
 nCount = Cnn1.getErrors().getCount(); 
 
 // If there are any errors in the collection, print them. 
 if( nCount > 0); 
 { 
 // Collection ranges from 0 to nCount - 1 
 for (i = 0; i< nCount; i++) 
 { 
 ErrItem = Cnn1.getErrors().getItem(i); 
 System.out.println("\t Error number: " + ErrItem.getNumber() 
 + "\t" + ErrItem.getDescription() ); 
 } 
 } 
 
 } 
 
 // PrintIOError Function 
 
 static void PrintIOError( java.io.IOException je) 
 { 
 System.out.println("Error \n"); 
 System.out.println("\tSource = " + je.getClass() + "\n"); 
 System.out.println("\tDescription = " + je.getMessage() + "\n"); 
 } 
} 
// EndOptimizeJ