OriginalValue and UnderlyingValue Properties Example (VJ++)

OriginalValue and UnderlyingValue Properties Example (VJ++)

This example demonstrates the OriginalValue and UnderlyingValue properties by displaying a message if a record's underlying data has changed during a Recordset batch update.

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

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

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

    // OriginalValueX function

    static void OriginalValueX()
    {
        // Define ADO Objects.
        Connection cnConn1 = null;
        Recordset rstTitles = null;
        Field fldType = null;

        // Declarations.
        String strCnn = "Provider=sqloledb;Data Source=srv;"
            + "Initial Catalog=Pubs;User Id=sa;Password=;";
        BufferedReader in = 
            new BufferedReader (new InputStreamReader(System.in));

        try
        {
            // Open a connection.
            cnConn1 = new Connection();
            cnConn1.open(strCnn);

            // Open recordset for batch update.
            rstTitles = new Recordset();
            rstTitles.setActiveConnection(cnConn1);
            rstTitles.setCursorType(AdoEnums.CursorType.KEYSET);
            rstTitles.setLockType(AdoEnums.LockType.BATCHOPTIMISTIC);
            rstTitles.open("Titles",cnConn1,
                           AdoEnums.CursorType.KEYSET,
                           AdoEnums.LockType.BATCHOPTIMISTIC,
                           AdoEnums.CommandType.TABLE);

            // Set field object variable for Type field.
            fldType = rstTitles.getField("type");

            // Change the type of psychology titles.
            while(!rstTitles.getEOF())
            {
                if(rstTitles.getField("type").getString().
                    trim().equals("psychology"))
                    fldType.setString("self_help");
                rstTitles.moveNext();
            }

            // Similate a change by another user by updating
            // data using a command string.
            cnConn1.execute("UPDATE Titles SET type = 'sociology' "
                                + "WHERE type = 'psychology'");

            // Check for changes.
            rstTitles.moveFirst();

            while(!rstTitles.getEOF())
            {
                String strOriginalValue = 
                    fldType.getOriginalValue().toString().trim();
                String strUnderlyingValue = 
                    fldType.getUnderlyingValue().toString().trim();
                if(!(strOriginalValue.equals(strUnderlyingValue)))
                {
                    System.out.println("Data has changed!" + "\n\n");
                    System.out.println("\tTitle ID: "
                        + rstTitles.getField("title_id").getString().trim() + 
                        "\n");
                    System.out.println("\tCurrent value: "
                            + fldType.getString()+ "\n");
                    System.out.println("\tOriginal value: "
                            + fldType.getOriginalValue().toString()+ "\n");
                    System.out.println("\tUnderlying value: "
                            + fldType.getUnderlyingValue().toString()+ "\n");
                    System.out.println("\n\nPress <Enter> to continue..");
                    in.readLine();
                }
                rstTitles.moveNext();
            }
            // Cancel the update because this is a demonstration.

            rstTitles.cancelBatch();
            rstTitles.close();

            // Restore original values.
            cnConn1.execute("UPDATE Titles SET type = 'psychology' "
                            + "WHERE type = 'sociology'");

            // Cleanup objects before exit.
            cnConn1.close();

        }
        catch( AdoException ae )
        {
            // Notify user of any errors that result from ADO.

            // As passing a Recordset, check for null pointer first.
            if (rstTitles!= null)
            {
                PrintProviderError(rstTitles.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");
    }
}