Task: Hash join



C#: using System;
using System.Collections.Generic;
using System.Linq;

namespace HashJoin
{
    public class AgeName
    {
        public AgeName(byte age, string name)
        {
            Age = age;
            Name = name;
        }
        public byte Age { get; private set; }
        public string Name { get; private set; }
    }

    public class NameNemesis
    {
        public NameNemesis(string name, string nemesis)
        {
            Name = name;
            Nemesis = nemesis;
        }
        public string Name { get; private set; }
        public string Nemesis { get; private set; }
    }

    public class DataContext
    {
        public DataContext()
        {
            AgeName = new List<AgeName>();
            NameNemesis = new List<NameNemesis>();
        }
        public List<AgeName> AgeName { get; set; }
        public List<NameNemesis> NameNemesis { get; set; }
    }

    public class AgeNameNemesis
    {
        public AgeNameNemesis(byte age, string name, string nemesis)
        {
            Age = age;
            Name = name;
            Nemesis = nemesis;
        }
        public byte Age { get; private set; }
        public string Name { get; private set; }
        public string Nemesis { get; private set; }
    }

    class Program
    {
        public static void Main()
        {
            var data = GetData();
            var result = ExecuteHashJoin(data);
            WriteResultToConsole(result);
        }

        private static void WriteResultToConsole(List<AgeNameNemesis> result)
        {
            result.ForEach(ageNameNemesis => Console.WriteLine("Age: {0}, Name: {1}, Nemesis: {2}",
                ageNameNemesis.Age, ageNameNemesis.Name, ageNameNemesis.Nemesis));
        }

        private static List<AgeNameNemesis> ExecuteHashJoin(DataContext data)
        {
            return (data.AgeName.Join(data.NameNemesis, 
                ageName => ageName.Name, nameNemesis => nameNemesis.Name,
                (ageName, nameNemesis) => new AgeNameNemesis(ageName.Age, ageName.Name, nameNemesis.Nemesis)))
                .ToList();
        }

        private static DataContext GetData()
        {
            var context = new DataContext();

            context.AgeName.AddRange(new [] {
                    new AgeName(27, "Jonah"), 
                    new AgeName(18, "Alan"), 
                    new AgeName(28, "Glory"), 
                    new AgeName(18, "Popeye"), 
                    new AgeName(28, "Alan")
                });

            context.NameNemesis.AddRange(new[]
            {
                new NameNemesis("Jonah", "Whales"),
                new NameNemesis("Jonah", "Spiders"),
                new NameNemesis("Alan", "Ghosts"),
                new NameNemesis("Alan", "Zombies"),
                new NameNemesis("Glory", "Buffy")
            });

            return context;
        }
    }
}






VB: Dim t_age(4,1)
t_age(0,0) = 27 : t_age(0,1) = "Jonah"
t_age(1,0) = 18 : t_age(1,1) = "Alan"
t_age(2,0) = 28 : t_age(2,1) = "Glory"
t_age(3,0) = 18 : t_age(3,1) = "Popeye"
t_age(4,0) = 28 : t_age(4,1) = "Alan"

Dim t_nemesis(4,1)
t_nemesis(0,0) = "Jonah" : t_nemesis(0,1) = "Whales"
t_nemesis(1,0) = "Jonah" : t_nemesis(1,1) = "Spiders"
t_nemesis(2,0) = "Alan" : t_nemesis(2,1) = "Ghosts"
t_nemesis(3,0) = "Alan" : t_nemesis(3,1) = "Zombies"
t_nemesis(4,0) = "Glory" : t_nemesis(4,1) = "Buffy"

Call hash_join(t_age,1,t_nemesis,0)

Sub hash_join(table_1,index_1,table_2,index_2)
	Set hash = CreateObject("Scripting.Dictionary")
	For i = 0 To UBound(table_1)
		hash.Add i,Array(table_1(i,0),table_1(i,1))
	Next
	For j = 0 To UBound(table_2)
		For Each key In hash.Keys
			If hash(key)(index_1) = table_2(j,index_2) Then
				WScript.StdOut.WriteLine hash(key)(0) & "," & hash(key)(1) &_
					" = " & table_2(j,0) & "," & table_2(j,1)
			End If
		Next
	Next
End Sub