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
              &nbs