获取两个DataTable的相同数据

public DataTable GetTable(DataTable FirstTable, DataTable SecondTable)
{
    DataTable ResultTable = FirstTable.Copy();

    if (FirstTable.Columns.Count != SecondTable.Columns.Count)
        return ResultTable;

    DataColumn[] keys = new DataColumn[ResultTable.Columns.Count];
    for (int k = 0; k < ResultTable.Columns.Count; k++)
    {
        keys[k] = ResultTable.Columns[k];
    }
    ResultTable.PrimaryKey = keys;
    ResultTable.Merge(SecondTable);
    return ResultTable;
}

public DataTable GetSameRecords(DataTable FirstTable, DataTable SecondTable)
{
    DataTable ResultTable = new DataTable("ResultTable");

    if (FirstTable.Columns.Count != SecondTable.Columns.Count)
        return ResultTable;

    DataSet ds = new DataSet();

    ds.Tables.AddRange(new DataTable[] { FirstTable.Copy(), SecondTable.Copy() });

    DataColumn[] firstColumns = new DataColumn[ds.Tables[0].Columns.Count];
    for (int i = 0; i < firstColumns.Length; i++)
    {
        firstColumns[i] = ds.Tables[0].Columns[i];
    }

    DataColumn[] secondColumns = new DataColumn[ds.Tables[1].Columns.Count];
    for (int i = 0; i < secondColumns.Length; i++)
    {
        secondColumns[i] = ds.Tables[1].Columns[i];
    }

    DataRelation r1 = new DataRelation(string.Empty, firstColumns, secondColumns, false);
    ds.Relations.Add(r1);

    DataColumn[] keys = new DataColumn[firstColumns.Length];
    for (int i = 0; i < firstColumns.Length; i++)
    {
        DataColumn dc = new DataColumn(firstColumns[i].ColumnName, firstColumns[i].DataType);
        ResultTable.Columns.Add(dc);
        keys[i] = dc;
    }
    ResultTable.PrimaryKey = keys;

    ResultTable.BeginLoadData();
    foreach (DataRow parentrow in ds.Tables[0].Rows)
    {
        DataRow[] childrows = parentrow.GetChildRows(r1);
        if (childrows != null && childrows.Length != 0 && ResultTable.Rows.Contains(parentrow.ItemArray) == false)
            ResultTable.LoadDataRow(parentrow.ItemArray, true);
    }
    ResultTable.EndLoadData();

    return ResultTable;
}