IDataStoreBase.RowsDiscard(int startrow, int endrow, DwBuffer bufferType) Method

.NET Standard 2.x

Discards a range of rows in the DataStore. Once a row has been discarded using RowsDiscard, you cannot restore the row unless you retrieve it again from the database.

Namespace: DWNet.Data

Assembly: DWNet.Data.dll

Syntax

  public bool RowsDiscard(int startrow, int endrow, DwBuffer buffer);

Parameters

startrow System.Int32

The zero-based index number of the first row you want to discard.

endrow System.Int32

The zero-based index number of the last row you want to discard.

bufferType DWNet.Data.DwBuffer

A value of the DwBuffer enumerated datatype specifying the DataWindow buffer containing the rows to be discarded.

Returns

System.Boolean

Returns true if it succeeds, and false if either startrow or endrow is not correct.

Remarks

Use the RowsDiscard method when your application is finished with some of the rows in a DataStore and you do not want an update to affect the rows in the database. For example, you can discard rows in the delete buffer, which prevents the rows from being deleted when you call the Update method.

Use the Reset method to clear all the rows from a DataStore.

Examples

The following code example demonstrates how to use the RowsDiscard method to delete multiple rows and keep only one row.

using DWNet.Data;
using System;

namespace Appeon.ApiDoc.IDataStoreBaseExamples
{
    public class RowsDiscardExample
    {
        private readonly SchoolContext _context;

        public RowsDiscardExample(SchoolContext dataContext)
        {
            // Sets the data context
            _context = dataContext;
        }

        public void Example()
        {
            // Instantiates a DataStore object with datawindow: d_department.
            var datastore = new DataStore("d_department", _context);

            datastore.Retrieve();

            Console.WriteLine("Before RowsDiscard, Rowcount: {0}",
                               datastore.RowCount);

            // Calls RowsDiscard to discard a range of rows in DataStore, the
            // discarded rows cannot be restored unless retrieved again from database.
            datastore.RowsDiscard(0, datastore.RowCount - 2, DwBuffer.Primary);

            Console.WriteLine("After RowsDiscard, PrimaryBuffer Rowcount: {0} ",
                               datastore.RowCount);

            Console.WriteLine("After RowsDiscard, DeleteBuffer Rowcount: {0}",
                               datastore.DeletedCount);

            /*This code produces the following output:
            
            Before RowsDiscard, Rowcount: 4
            After RowsDiscard, PrimaryBuffer Rowcount: 1
            After RowsDiscard, DeleteBuffer Rowcount: 0            
            */

        }
    }
}

Example Refer To

Model Class: D_Department
DataWindow File: d_department

Applies to

.NET Standard

2.x