Delete Method Example (VJ++)

Delete Method Example (VJ++)

This example uses the Delete method to remove a specified record from a Recordset.

// The WFC class includes the ADO objects.

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

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

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

    // DeleteX function

    static void DeleteX()
    {

        // Define ADO Objects.
        Recordset rstRoySched = null;

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

        String  strMessage="";
        String  strTitleID;
        int intLoRange =0;
        int intHiRange =0;
        int intRoyalty =0;
        boolean bolFound;

        try
        {
            rstRoySched = new Recordset();
            rstRoySched.setCursorLocation(AdoEnums.CursorLocation.CLIENT);
            rstRoySched.setCursorType(AdoEnums.CursorType.STATIC);
            rstRoySched.setLockType(AdoEnums.LockType.BATCHOPTIMISTIC);

            // Open RoySched table.
            rstRoySched.open("SELECT * FROM roysched " +
                "WHERE royalty = 20", strCnn,
                AdoEnums.CursorType.STATIC,
                AdoEnums.LockType.BATCHOPTIMISTIC,
                AdoEnums.CommandType.TEXT);

            // Prompt for a record to delete.
            strMessage = "Before delete there are "
                + rstRoySched.getRecordCount()
                + " titles with 20 percent royalty:" + "\n\n";
            while(!rstRoySched.getEOF())
            {
                strMessage += rstRoySched.getField("title_id").getString() + 
                    "\n\n";
                rstRoySched.moveNext();
            }
            strMessage += "Enter the ID of a record to delete:" + "\n";
            System.out.println(strMessage);
            strTitleID = in.readLine().trim().toUpperCase();

            // Move to the record and save data so it can be restored.
            rstRoySched.setFilter("title_id = '" + strTitleID + "'");
            if(!(rstRoySched.getRecordCount()==0))
            {
                intLoRange = rstRoySched.getField("lorange").getInt();
                intHiRange = rstRoySched.getField("hirange").getInt();
                intRoyalty = rstRoySched.getField("royalty").getInt();
                bolFound = true;
            }
            else
            {
                System.out.println("\nIncorrect ID. No Record deleted." );
                bolFound = false;
            }

            // Delete the record.
            if(bolFound)
            {
                rstRoySched.delete();
                rstRoySched.updateBatch();
            }
            // Show the results.
            rstRoySched.setFilter(new Integer(AdoEnums.FilterGroup.NONE));
            rstRoySched.requery();
            strMessage ="";
            strMessage = "\n\nAfter delete there are "
                + rstRoySched.getRecordCount()
                + " titles with 20 percent royalty:" + "\n\n";
            while(!rstRoySched.getEOF())
            {
                strMessage += rstRoySched.getField("title_id").getString() + 
                    "\n\n";
                rstRoySched.moveNext();
            }
            System.out.println(strMessage);
            System.out.println("\nPress <Enter> to continue..");
            in.readLine();

            // Restore the data because this is a demonstration.
            if(bolFound)
            {
                rstRoySched.addNew();
                rstRoySched.getField("title_id").setString(strTitleID);
                rstRoySched.getField("lorange").setInt(intLoRange);
                rstRoySched.getField("hirange").setInt(intHiRange);
                rstRoySched.getField("royalty").setInt(intRoyalty);
                rstRoySched.updateBatch();
            }

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

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

            // As passing a Recordset, check for null pointer first.
                if (rstRoySched != null)
                {
                    PrintProviderError(rstRoySched.getActiveConnection());
                    System.out.println("Exception: " + ae.getMessage());
                }
                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");
    }
}