选择TOP 5 *从SomeTable，使用Dataview.RowFilter？ [英] Select TOP 5 * from SomeTable, using Dataview.RowFilter?

问题描述

我需要选择5从缓存数据视图对象的最新行，有没有办法做到这一点？

I need to select 5 most recent rows from cached Dataview object, is there any way to do that?

我做过尝试，但索引的DataColumn是空的。

I've tried but Indexer DataColumn is empty. :

public static DataView getLatestFourActive()
{
    DataTable productDataTable = getAll().ToTable();
    DataColumn ExpressionColumn = new DataColumn("Indexer",typeof(System.Int32));
    ExpressionColumn.Unique = true;
    ExpressionColumn.AutoIncrement = true;
    ExpressionColumn.AllowDBNull = false;
    ExpressionColumn.AutoIncrementSeed = 0;
    ExpressionColumn.AutoIncrementStep = 1;
    productDataTable.Columns.Add(ExpressionColumn);

    DataView productFilteredView = productDataTable.DefaultView;
    productFilteredView.RowFilter = "isActive=1 and Indexer<4";
    return productFilteredView;
}

GETALL（）返回缓存的数据视图

getAll() returns cached DataView

感谢

推荐答案

我遇到了同样的样品上面的这篇文章，但过去后说，所提供的code不起作用。

I encountered the same sample above in this article, but the last post says the provided code doesn't work.

然而，这篇文章有一个解决方案，它的工作，所以这里的code您可以使用：

However, this article has a solution that does work, so here's the code you could use:

public static DataView getLatestFourActive() {
    DataTable productDataTable = getAll().ToTable();
    DataTable cloneDataTable = productDataTable.Clone();

    for (int i = 0; i < 4; i++) {
        cloneDataTable.ImportRow(productDataTable.Rows[i]);
    }       
    return new DataView(cloneDataTable);
}

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