private DataTable Join(DataTable first, DataTable second, DataColumn[] FJC, DataColumn[] SJC)
    {
        //将两个表根据某列关联生成一个表
        DataTable table = new DataTable("Join");
        try
        {
            DataSet ds = new DataSet();
            DataTable[] dt ={ first.Copy(), second.Copy() };
            //将两个表存入到Dataset中

            ds.Tables.AddRange(dt);

            DataColumn[] parentcolumns = new DataColumn[FJC.Length];
            for (int i = 0; i < parentcolumns.Length; i++)
            {
                parentcolumns[i] = ds.Tables[0].Columns[FJC[i].ColumnName];

            }
            DataColumn[] childcolumns = new DataColumn[SJC.Length];

            for (int i = 0; i < childcolumns.Length; i++)
            {
                childcolumns[i] = ds.Tables[1].Columns[SJC[i].ColumnName];
            }
            //设置两表中的关系．

            DataRelation r = new DataRelation(string.Empty, parentcolumns, childcolumns, false);
            ds.Relations.Add(r);
            for (int i = 0; i < first.Columns.Count; i++)
            {
                table.Columns.Add(first.Columns[i].ColumnName, first.Columns[i].DataType);
            }
            for (int i = 0; i < second.Columns.Count; i++)
            {
                if (!table.Columns.Contains(second.Columns[i].ColumnName))
                {
                    table.Columns.Add(second.Columns[i].ColumnName, second.Columns[i].DataType);
                }
                else
                {
                    table.Columns.Add(second.Columns[i].ColumnName + "_Second", second.Columns[i].DataType);

                }
            }
            table.BeginLoadData();
            foreach (DataRow firstrow in ds.Tables[0].Rows)
            {
                DataRow[] childrows = firstrow.GetChildRows(r);
                if (childrows != null && childrows.Length > 0)
                {
                    object[] parentarray = firstrow.ItemArray;
                    foreach (DataRow secondrow in childrows)
                    {
                        object[] secondarray = secondrow.ItemArray;
                        object[] joinarray = new object[parentarray.Length + secondarray.Length];
                        Array.Copy(parentarray, 0, joinarray, 0, parentarray.Length);
                        Array.Copy(secondarray, 0, joinarray, parentarray.Length, secondarray.Length);
                        table.LoadDataRow(joinarray, true);
                    }
                }
                else
                {
                        object[] parentarray = firstrow.ItemArray;
                        DataRow secondrow=second.NewRow();
                        object[] secondarray = secondrow.ItemArray;
                        object[] joinarray = new object[parentarray.Length + secondarray.Length];
                        Array.Copy(parentarray, 0, joinarray, 0, parentarray.Length);
                        Array.Copy(secondarray, 0, joinarray, parentarray.Length, secondarray.Length);
                        table.LoadDataRow(joinarray, true);
                   
                }
            }
            table.EndLoadData();
        }
        catch (Exception e)
        {
            Response.Write(e.ToString());
        }
        return table;
    }
    private DataTable Join(DataTable first, DataTable second, DataColumn FJC, DataColumn SJC)
    {
        return Join(first, second, new DataColumn[] { FJC }, new DataColumn[] { SJC });
    }
    private DataTable Join(DataTable first, DataTable second, string FJC, string SJC)
    {
        return Join(first, second, new DataColumn[] { first.Columns[FJC] }, new DataColumn[] { first.Columns[SJC] });
    }