[英]Returning data related to a day without duplication using linq and C#
下面的查詢返回下面的示例數據。 有很多天。 我希望能夠顯示每天以及每天下的相關數據。 我的預期結果也可以在下面找到。 我以某種方式認為我需要使用嵌套的foreach語句,但無法弄清楚這一點。 我是Linq的新手。 如果您有任何想法,請協助。
var pracResult = from t in queryResultFilter
orderby t.Day
select t;
Int32 okeke = 0;
foreach (MyPlanDto chk in pracResult)
{
okeke = chk.Day;
}
Sample data
*************
Day = Monday
CustomerNumber = 1001
Product = Dress
Day = Tuesday
customerNumber = 1002
Product = Boxers
Day = Wednesday
CustomerNumber = 1003
Product = Pencil
Day = Monday
CustomerNumber = 1006
Product = Pen
Day = Monday
CustomerNumber = 1007
Product = Book
Day = Tuesday
CustomerNumber = 1008
Product = Erazer
Result:
********
Monday
********
CustomerNumber = 1001
Product = Dress
CustomerNumber = 1006
Product = Pen
CustomerNumber = 1007
Product = Book
Tuesday
********
customerNumber = 1002
Product = Boxers
CustomerNumber = 1008
Product = Erazer
Wednesday
***********
CustomerNumber = 1003
Product = Pencil
這是我嘗試但不起作用的示例。
using System;
using System.Collections.Generic;
using System.Linq;
namespace MasterData
{
class Program
{
static void Main(string[] args)
{
var queryResultFilter = ObjMyPlan();
var pracResult = (from t in queryResultFilter
orderby t.Day
select t).ToLookup(p => p.Day).Select(col1 => col1.First());
var pracResult2 = (from t in queryResultFilter
orderby t.Day
select t);
foreach (MyPlanDto chk in pracResult)
{
Console.WriteLine(chk.Day);
foreach (MyPlanDto obj1 in pracResult2)
{
var yoyou = (from t in pracResult2
select t).Where(p=>p.Day.Equals(chk.Day));
Console.WriteLine("Customer Number:" + obj1.CustomerNumber + "Product:" + obj1.Product);
}
}
Console.ReadKey();
}
static List<MyPlanDto> ObjMyPlan()
{
List<MyPlanDto> objResult = new List<MyPlanDto>();
objResult.Add(new MyPlanDto(){Day = "Monday", CustomerNumber = "1001", Product = "Dress"});
objResult.Add(new MyPlanDto(){Day = "Tuesday", CustomerNumber = "1002", Product = "Boxers"});
objResult.Add(new MyPlanDto(){Day = "Wednesday", CustomerNumber = "1003", Product = "Pencil"});
objResult.Add(new MyPlanDto(){Day = "Monday", CustomerNumber = "1006", Product = "Pen"});
objResult.Add(new MyPlanDto(){Day = "Monday", CustomerNumber = "1007", Product = "Book"});
objResult.Add(new MyPlanDto(){Day = "Tuesday", CustomerNumber = "1008", Product = "Erazer"});
return objResult;
}
}
}
您已接近ToLookup
方法。 您應該能夠使用如下查詢:
var query = queryResultFilter.OrderBy(t => t.Day)
.ToLookup(t => t.Day);
foreach (var group in query) {
Console.WriteLine(group.Key);
foreach (var item in group) {
Console.WriteLine("CustomerNumber: {0}", item.CustomerNumber);
Console.WriteLine("Product: {0}", item.Product);
}
Console.WriteLine();
}
或者,通常想到的第一個選擇是使用分組,與ToLookup
相比,分組提供了延遲執行。 這些查詢中的任何一個都可以工作(並且您可以使用上面相同的foreach
循環):
var query = queryResultFilter.OrderBy(t => t.Day)
.GroupBy(t => t.Day);
// query syntax
var query = from t in queryResultFilter
orderby t.Day
group t by t.Day into grouped
select grouped;
如果您對ToLookup
和GroupBy
之間的差異感到好奇,請查看這篇文章 。
請注意,按t.Day
排序是按字母順序進行的,因此它確實符合您的t.Day
目的嗎? 如果您的數據中包含“星期五”,則在訂購時它將顯示在“星期三”之前。 如果您有日期,那么如果您確實需要訂購結果,那會更好。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.