Firstly, I just cannot explain my question in the title properly, but I don't think its a duplicate. I have a List of model which id like to group by multiple fields, then count them into new field, and keep all the other field in the result. I am sorry for the bad explanation, I've been researching how to do this for hours and I just cannot figure it out.. I would like to get from this :

Grouped by SaleID and PrintType into Something like this :

Preferably id like to use LINQ, but id be good with SQL too, id just like to avoid using a for loop if possible. Edit.: There are a set number of printtypes so it wouldn't need to be dynamic.

CodePudding user response：

In order to aggregate the data for a set number of PrintTypes, you can group by SaleId as the additional data like address, phone and product are the same for a SaleId (based on your sample data).

var aggregated = from x in GenerateSales() 
    group x by x.SaleId into g // Assume that SaleId is the key that you want to group by
    select new Aggregate() 
    { 
        SaleId = g.Key, 
        // Additional data that are the same for all rows with the same SaleId
        Name = g.First().Name, 
        Product = g.First().Product, 
        Address = g.First().Address, 
        Phone = g.First().Phone, 
        // Calculate counts of Print Types
        NoOfPrintType1 = g.Where(x => x.PrintType == "PrintType1").Count(),
        NoOfPrintType2 = g.Where(x => x.PrintType == "PrintType2").Count(),
        NoOfPrintType3 = g.Where(x => x.PrintType == "PrintType3").Count(),
    };

The Linq statement first groups by SaleId and then creates an object for each SaleId, that comprises

• the SaleId
• the additional data like address, phone...
• the count for each known PrintType (calculated by filtering the items of the group and then counting the rows)

Below you can find a sample that generates test data and outputs the result.

Result

112 | Joe | Apple | New street 12 | 11223344 | 1 | 3 | 1
113 | Joe | Kiwi | New street 12 | 11223344 | 0 | 0 | 1
114 | Jane | Orange | New street 19 | 72754722 | 1 | 0 | 0
115 | John | Orange | New street 11 | 99236527 | 0 | 2 | 0

Sample code

using System;
using System.Collections.Generic;
using System.Linq;

namespace LinqTest
{
    class Sale 
    {
        public string SaleId { get; set; }
        public string Name { get; set; }
        public string Product { get; set; }
        public string Address { get; set; }
        public string Phone { get; set; }
        public string PrintType { get; set; }
    }

    class Aggregate 
    {
        public string SaleId { get; set; }
        public string Name { get; set; }
        public string Product { get; set; }
        public string Address { get; set; }
        public string Phone { get; set; }
        public int NoOfPrintType1 { get; set; }
        public int NoOfPrintType2 { get; set; }
        public int NoOfPrintType3 { get; set; }

        public override string ToString() 
        {
            return $"{SaleId} | {Name} | {Product} | {Address} | {Phone} | {NoOfPrintType1} | {NoOfPrintType2} | {NoOfPrintType3}";
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var aggregated = from x in GenerateSales() 
                group x by x.SaleId into g // Assume that SaleId is the key that you want to group by
                select new Aggregate() 
                { 
                    SaleId = g.Key, 
                    // Additional data that are the same for all rows with the same SaleId
                    Name = g.First().Name, 
                    Product = g.First().Product, 
                    Address = g.First().Address, 
                    Phone = g.First().Phone, 
                    // Calculate counts of Print Types
                    NoOfPrintType1 = g.Where(x => x.PrintType == "PrintType1").Count(),
                    NoOfPrintType2 = g.Where(x => x.PrintType == "PrintType2").Count(),
                    NoOfPrintType3 = g.Where(x => x.PrintType == "PrintType3").Count(),
                };
            foreach(var a in aggregated)
            {
                Console.WriteLine(a.ToString());
            }
        }

        static IEnumerable<Sale> GenerateSales()
        {
            yield return new Sale() { SaleId = "112", Name = "Joe", Product = "Apple", Address = "New street 12", Phone = "11223344", PrintType = "PrintType1" };
            yield return new Sale() { SaleId = "112", Name = "Joe", Product = "Apple", Address = "New street 12", Phone = "11223344", PrintType = "PrintType2" };
            yield return new Sale() { SaleId = "112", Name = "Joe", Product = "Apple", Address = "New street 12", Phone = "11223344", PrintType = "PrintType2" };
            yield return new Sale() { SaleId = "112", Name = "Joe", Product = "Apple", Address = "New street 12", Phone = "11223344", PrintType = "PrintType2" };
            yield return new Sale() { SaleId = "112", Name = "Joe", Product = "Apple", Address = "New street 12", Phone = "11223344", PrintType = "PrintType3" };
            yield return new Sale() { SaleId = "113", Name = "Joe", Product = "Kiwi", Address = "New street 12", Phone = "11223344", PrintType = "PrintType3" };
            yield return new Sale() { SaleId = "114", Name = "Jane", Product = "Orange", Address = "New street 19", Phone = "72754722", PrintType = "PrintType1" };
            yield return new Sale() { SaleId = "115", Name = "John", Product = "Orange", Address = "New street 11", Phone = "99236527", PrintType = "PrintType2" };
            yield return new Sale() { SaleId = "115", Name = "John", Product = "Orange", Address = "New street 11", Phone = "99236527", PrintType = "PrintType2" };
        }
    }
}

CodePudding user response：

you can use this SQL query

with x as (
   SELECT  [SaleID],[Name],[Product],[Address],[Phone],[PrintType]
          ,case when [PrintType]='PrintType1' then count(*) else 0 end NoOfPrintType1
          ,case when [PrintType]='PrintType2' then count(*) else 0 end NoOfPrintType2
          ,case when [PrintType]='PrintType3' then count(*) else 0 end NoOfPrintType3
      FROM [Table_1]
      group by [SaleID] ,[Name],[Product],[Address],[Phone] ,[PrintType])
    
    select [SaleID],[Name],[Product],[Address],[Phone]
          ,sum(NoOfPrintType1)NoOfPrintType1
          ,sum(NoOfPrintType2)NoOfPrintType2
          ,sum(NoOfPrintType3)NoOfPrintType3 from x
   group by [SaleID]
          ,[Name],[Product],[Address],[Phone]