進行兩個序列的串聯，是比較相似聯合操作在其操作，但這不會刪除重複記錄。

操作	描述	C#查詢表達式語法	VB查詢表達式語法
Concat	兩個序列被連接為一個單一的一個序列的形成。	不適用	不適用

Concat例子 - Enumerable.Concat(Tsource)方法

C#

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

namespace Operators
{
  class Concat
  {
     static void Main(string[] args)
     {
        Pet[] cats = GetCats();
        Pet[] dogs = GetDogs();

        IEnumerable<string> query = cats.Select(cat => cat.Name).Concat(dogs.Select(dog => dog.Name));

        foreach (var e in query)
        {
           Console.WriteLine("Name = {0} ", e);
        }

        Console.WriteLine("\nPress any key to continue.");
        Console.ReadKey();
     }

     static Pet[] GetCats()
     {
        Pet[] cats = { new Pet { Name="Barley", Age=8 },
                       new Pet { Name="Boots", Age=4 },
                       new Pet { Name="Whiskers", Age=1 } };
                     return cats;
     }

     static Pet[] GetDogs()
     {
        Pet[] dogs = { new Pet { Name="Bounder", Age=3 },
                       new Pet { Name="Snoopy", Age=14 },
                       new Pet { Name="Fido", Age=9 } };
                     return dogs;
     }
  }

  class Pet
  {
     public string Name { get; set; }
     public int Age { get; set; }
  }
}

VB

Module Module1

  Sub Main()

     Dim cats As List(Of Pet) = GetCats()
     Dim dogs As List(Of Pet) = GetDogs()

     Dim list = cats.Cast(Of Pet)().Concat(dogs.Cast(Of Pet)()).ToList()

     For Each e In list
        Console.WriteLine("Name = {0}", e.Name)
     Next

     Console.WriteLine(vbLf & "Press any key to continue.")
     Console.ReadKey()
  End Sub

  Function GetCats() As List(Of Pet)

     Dim cats As New List(Of Pet)

        cats.Add(New Pet With {.Name = "Barley", .Age = 8})
        cats.Add(New Pet With {.Name = "Boots", .Age = 4})
        cats.Add(New Pet With {.Name = "Whiskers", .Age = 1})

        Return cats
  End Function

  Function GetDogs() As List(Of Pet)

     Dim dogs As New List(Of Pet)

        dogs.Add(New Pet With {.Name = "Bounder", .Age = 3})
        dogs.Add(New Pet With {.Name = "Snoopy", .Age = 14})
        dogs.Add(New Pet With {.Name = "Fido", .Age = 9})

        Return dogs
  End Function

  Class Pet
     Public Property Name As String
     Public Property Age As Integer
  End Class
End Module

當在C＃或VB上麵的代碼被編譯和執行時，它產生了以下結果：

Barley 
Boots 
Whiskers 
Bounder 
Snoopy 
Fido

Press any key to continue.