2个或多个datable类似于sql inner join 合并查询

 public static DataTable DatableInnerJoin(DataTable FirstTB, DataTable SecondTB, DataColumn[] FJC, DataColumn[] SJC)
    {
        if (FirstTB == null || SecondTB == null)
            return null;
        if (FJC == null || FJC.Length <= 0)
            return null;
        if (SJC == null || SJC.Length <= 0)
            return null;
        DataTable table = new DataTable("Join");
        using (DataSet ds = new DataSet())
        {
            ds.Tables.AddRange(new DataTable[] { FirstTB.Copy(), SecondTB.Copy() });
            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];
            }
            DataRelation relation = new DataRelation("Relation_Table", parentcolumns, childcolumns, false);
            ds.Relations.Add(relation);
            for (int i = 0; i < FirstTB.Columns.Count; i++)
            {
                table.Columns.Add(FirstTB.Columns[i].ColumnName, FirstTB.Columns[i].DataType);
            }

            for (int i = 0; i < SecondTB.Columns.Count; i++)
            {
                if (!table.Columns.Contains(SecondTB.Columns[i].ColumnName))
                    table.Columns.Add(SecondTB.Columns[i].ColumnName, SecondTB.Columns[i].DataType);
                else
                    table.Columns.Add(SecondTB.Columns[i].ColumnName + "_Second", SecondTB.Columns[i].DataType);
            }
            table.BeginLoadData();
            foreach (DataRow firstrow in ds.Tables[0].Rows)
            {
                DataRow[] childrows = firstrow.GetChildRows(relation);
                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);
                    }
                }
            }
            table.EndLoadData();
        }
        return table;
    }