C# 中两个DataTable join 连接

/// <summary>
        /// 连接两个表
        /// </summary>
        /// <param name="First"></param>
        /// <param name="Second"></param>
        /// <param name="FJC"></param>
        /// <param name="SJC"></param>
        /// <returns></returns>
        public static DataTable JoinTwoTable(DataTable First, DataTable Second, string FJC, string SJC)
        {
            return JoinTwoTable(First, Second, new DataColumn[] { First.Columns[FJC] }, new DataColumn[] { First.Columns[SJC] });
        }


        /// <summary>
        /// 连接两个表
        /// </summary>
        /// <param name="First"></param>
        /// <param name="Second"></param>
        /// <param name="FJC"></param>
        /// <param name="SJC"></param>
        /// <returns></returns>
        protected static DataTable JoinTwoTable(DataTable First, DataTable Second, DataColumn FJC, DataColumn SJC)
        {
            return JoinTwoTable(First, Second, new DataColumn[] { FJC }, new DataColumn[] { SJC});
        }

        /// <summary>
        /// 连接两个Table
        /// </summary>
        /// <param name="First"></param>
        /// <param name="Second"></param>
        /// <param name="FJC"></param>
        /// <param name="SJC"></param>
        /// <returns></returns>
        protected static DataTable JoinTwoTable(DataTable First, DataTable Second, DataColumn[] FJC, DataColumn[] SJC)
        {

            //创建一个新的DataTable
            DataTable table = new DataTable("Join");

            using (DataSet ds = new DataSet())
            {

                //把DataTable Copy到DataSet中
                ds.Tables.AddRange(new DataTable[] { First.Copy(), Second.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];
                }


                //创建关联

                DataRelation r = new DataRelation(string.Empty, parentcolumns, childcolumns, false);
                ds.Relations.Add(r);


                //为关联表创建列
                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++)
                {
                    //看看有没有重复的列，如果有在第二个DataTable的Column的列明后加_Second
                    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)
                {
                    //得到行的数据
                    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);
                        }
                    }
                }

                table.EndLoadData();
            }


            return table;

        }