Linq查询DataTable

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本文介绍使用C#进行DataTable数据处理的方法，包括筛选特定条件的记录、计算两个列表的差集、聚合计算及数据转换等高级LINQ查询技巧。通过具体示例，展示了如何高效地操作数据。

 string str = (from DataRow r in table.Rows//table为DataTable类型
                              where r.Field<string>("A") == "1034"
                              select r.Field<string>("B")).FirstOrDefault();

m_Su = m_newListKsh.Except(m_listKsh).ToList();//取两个list差集   

            var query = from r in newDt.AsEnumerable()
                          where m_Su.Contains(r.Field<string>("KSH"))
                          select r;
            DataTable dtFinal = query.CopyToDataTable<DataRow>();

int bds= (from DataRow row in dt.Rows
                                                          where row.Field<string>("NewSFBD") == "是"
                                                          select new { qsum = row["KSH"] }).Sum(a => Convert.ToInt32(a.qsum) );

int sfCount = dt.AsEnumerable().Select(d => d.Field<string>("NewLYSF")).Distinct().ToList().Count;

 List<string> lzzh20 = listZhs20.Where(x => Convert.ToDouble(x) > 180).ToList();

   List<string> existingCodeList = new List<string>();
   Dictionary<string, string> existingCodeDictionary = new Dictionary<string, string>();

   existingCodeList = viewMode.FeeSubject.Where(x => !string.IsNullOrEmpty(x.Code)).Select(x => x.FeeCode).ToList();

   existingCodeDictionary = viewMode.FeeSubject.Where(x => !string.IsNullOrEmpty(x.Code)).Select(x => new { Key = x.FeeCode, Value = x.Code }).ToDictionary(c => c.Key, c => c.Value);