MDAC 2.5 SDK - ADO

CompareBookmarks Method Example (VJ++)

See Also

This example demonstrates the CompareBookmarks method. The relative value of bookmarks is seldom needed unless a particular bookmark is somehow special.

Designate a random row of a Recordset derived from the Authors table as the target of a search. Then display the position of each row relative to that target.

import com.ms.wfc.data.*;
import java.io.* ;
import com.ms.com.*;

public class CompareBookmarksX //
{
   // The main entry point for the application.

   public static void main (String[] args)
   {
      CompareBookmarksX();
      System.exit(0);
   }

   // CompareBookmarksX function

   static void CompareBookmarksX()
   {
      // Define ADO Objects.
      Recordset rstAuthors = null;

      // Declarations.
      BufferedReader in =
         new BufferedReader (new InputStreamReader(System.in));
      String strCnn = "DSN=Pubs;Provider=MSDASQL;uid=sa;pwd=;";
      int intCount;
      Variant varTarget = null;
      int intResult;
      String strAns;
      int intDisplaySize = 15;

      try
      {
         rstAuthors = new Recordset();
         rstAuthors.open("SELECT * FROM authors",
            strCnn,
            AdoEnums.CursorType.STATIC,
            AdoEnums.LockType.READONLY,
            AdoEnums.CommandType.TEXT);
         intCount = rstAuthors.getRecordCount();
         System.out.println("Rows in the Recordset = " +
            Integer.toString(intCount));

         // Exit if an empty recordset.
         if(intCount == 0)
            System.exit(0);

         // Randomize.
         intCount = (int)(intCount * Math.random());
         // Get position between 0 and count-1.
         System.out.println("\nRandomly chosen row position = " +
            Integer.toString(intCount)+ "\n");
         rstAuthors.move(intCount,new Integer(AdoEnums.Bookmark.FIRST));          // Move row to random position.
         varTarget = (Variant)rstAuthors.getBookmark();
         // Remember the mystery row.
         intCount = 0;
         rstAuthors.moveFirst();

         // Loop through recordset.
         while(!rstAuthors.getEOF())
         {
            intResult = rstAuthors.compareBookmarks
               ((Variant)rstAuthors.getBookmark(), varTarget);
            if(intResult == AdoEnums.Compare.NOTEQUAL)
               System.out.println("Row " +
                  Integer.toString(intCount) +
                  ": Bookmarks are not equal.");
            else if(intResult == AdoEnums.Compare.NOTCOMPARABLE)
               System.out.println("Row " +
                  Integer.toString(intCount) +
                  ": Bookmarks are not comparable.");
            else
            {
               switch(intResult)
               {
               case AdoEnums.Compare.LESSTHAN :
                  strAns = "less than";
                  break;
               case AdoEnums.Compare.EQUAL :
                  strAns = "equal to";
                  break;
               case AdoEnums.Compare.GREATERTHAN :
                  strAns = "greater than";
                  break;
               default :
                  strAns = "in error comparing to";
                  break;
               }
               System.out.println("Row position " +
                  Integer.toString(intCount) +
                  " is " + strAns + " the target.");
            }
            if(intCount % intDisplaySize == 0 && intCount > 0)
            {
               System.out.println("\nPress <Enter> to continue..");
               in.readLine();
            }
            intCount++;
            rstAuthors.moveNext();
         }

         // Cleanup objects before exit.
         rstAuthors.close();
         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);
      }
   }

   // PrintProviderError Function

   static void PrintProviderError( Connection Cnn1 )
   {
      // Print Provider errors from Connection object.
      // ErrItem is an item object in the Connection’s 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");
   }
}