DataTable,List去重複記錄的方法

List<OUTP_DRUGITEM> LDrugitem_all = query1.ToList(); OrderDrugitem_yp = LDrugitem_all.Distinct(new Comparint()).ToList();//DISTINCT /// <summary> /// LINQEntityDistinct顯示字段唯一值記錄 /// </summary> internal class Comparint : IEqualityComparer<OUTP_DRUGITEM> { public bool Equals(OUTP_DRUGITEM x, OUTP_DRUGITEM y) { if (x == null && y == null) return false; return (x.IDM == y.IDM); } public int GetHashCode(OUTP_DRUGITEM obj) { return obj.ToString().GetHashCode(); } }

List去重複記錄的方法

 

 

using System.Collections.Generic; using System.Linq; using System.Data; using System; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { DataTable tbl = new DataTable(); tbl.Columns.Add("Id", typeof(System.Int32)); tbl.Columns.Add("City", typeof(System.String)); tbl.Columns.Add("Province", typeof(System.String)); tbl.Rows.Add(1, "武漢", "湖北"); tbl.Rows.Add(2, "應城", "湖北"); tbl.Rows.Add(3, "武漢", "湖北"); IEnumerable <DataRow> r = tbl.AsEnumerable().Distinct(new CityComparer()); //到這一步,r裏就是去重複的記錄了 foreach (var item in r) { Console.WriteLine(item["Id"] + "，" + item["City"] + "，" + item["Province"]); } Console.ReadLine(); } } class CityComparer : IEqualityComparer <DataRow> { public bool Equals(DataRow r1, DataRow r2) { return r1["City"] == r2["City"]; } public int GetHashCode(DataRow obj) { return obj.ToString().GetHashCode(); } } }

 

上面的代碼，將DataTable中"城市名"重複的記錄去掉了

 

 

如何去掉DataTable裏重複的記錄(DataTable是返回過來的，不能再重新查詢數據庫，所以無法用sql中的select distinct xxx處理，只能在DataTable上動腦筋) 

思路：將DataTable轉成IEnumerable，然後就能調用Distinct方法了