Prepared-Eigenschaft (Beispiel) (VJ++)

Gilt für: Access 2013, Office 2013

Dieses Beispiel veranschaulicht die Prepared-Eigenschaft, indem zwei Command-Objekte geöffnet werden: ein vorbereitetes und ein nicht vorbereitetes Objekt.

 
// BeginPreparedJ 
import com.ms.wfc.data.*; 
import java.io.* ; 
 
public class PreparedX 
{ 
 // The main entry point for the application. 
 
 public static void main (String[] args) 
 { 
 PreparedX(); 
 System.exit(0); 
 } 
 
 // PreparedX function 
 
 static void PreparedX() 
 { 
 // Define string variables. 
 String strCnn = "Provider='sqloledb';Data Source='MySqlServer';" 
 + "Initial Catalog='Pubs';Integrated Security='SSPI';"; 
 String strCmd = "SELECT title, type FROM Titles ORDER BY type"; 
 
 // Define ADO Objects. 
 Connection cnConn1 = null; 
 Command cmd1 = null; 
 Command cmd2 = null; 
 
 // Declarations. 
 BufferedReader in = 
 new BufferedReader (new InputStreamReader(System.in)); 
 long timeStart; 
 long timeEnd; 
 float timeNotPrepared ; 
 float timePrepared; 
 int intLoop; 
 String strTemp; 
 
 try 
 { 
 // Open a connection. 
 cnConn1 = new Connection(); 
 cnConn1.open(strCnn); 
 
 // Create two command objects for the same 
 // command - one prepared and one not prepared. 
 cmd1 = new Command(); 
 cmd1.setActiveConnection(cnConn1); 
 cmd1.setCommandType(AdoEnums.CommandType.TEXT); 
 cmd1.setCommandText(strCmd); 
 
 cmd2 = new Command(); 
 cmd2.setActiveConnection(cnConn1); 
 cmd2.setCommandType(AdoEnums.CommandType.TEXT); 
 cmd2.setCommandText(strCmd); 
 cmd2.setPrepared(true); 
 
 // Set a timer, then execute the unprepared 
 // command 20 times. 
 timeStart = System.currentTimeMillis(); 
 for ( intLoop = 0; intLoop < 20; intLoop++) 
 cmd1.execute(); 
 timeEnd = System.currentTimeMillis(); 
 timeNotPrepared =(float)(timeEnd - timeStart)/1000f; 
 
 // Reset the timer, then execute the prepared 
 // command 20 times. 
 timeStart = System.currentTimeMillis(); 
 for ( intLoop = 0; intLoop < 20; intLoop++) 
 cmd2.execute(); 
 timeEnd = System.currentTimeMillis(); 
 timePrepared =(float)(timeEnd - timeStart)/1000f; 
 
 // Display performance results. 
 System.out.println("\nPerformance Results:"); 
 System.out.println("\n\tNot Prepared: " + timeNotPrepared + 
 " seconds"); 
 System.out.println("\n\tPrepared: " + timePrepared + 
 " seconds"); 
 System.out.println("\n\nPress <Enter> to continue.."); 
 in.readLine(); 
 
 } 
 catch( AdoException ae ) 
 { 
 // Notify user of any errors that result from ADO. 
 
 // As passing a Connection, check for null pointer first. 
 if (cnConn1!= null) 
 { 
 PrintProviderError(cnConn1); 
 } 
 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 (cnConn1 != null) 
 if (cnConn1.getState() == 1) 
 cnConn1.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"); 
 } 
} 
// EndPreparedJ