C# DataTable中根据某一列值 生成到新的列中

1 DataSet ds = devBll.GetDevMapInfo(state);
2                 ds.Tables[0].Columns.Add(new DataColumn("Show", typeof(bool)) { Expression= "IIF(MarkerIcon<>NULL,false,false)" });
3                 ds.Tables[1].Columns.Add(new DataColumn("Show", typeof(bool)) { Expression = "IIF(MarkerIcon<>NULL,false,false)" });
4                 ds.Tables[2].Columns.Add(new DataColumn("Show", typeof(bool)) { Expression = "IIF(MarkerIcon<>NULL,false,false)" });