在LINQ中，交叉连接是一个过程，其中两个序列的元素相互组合，这意味着第一个序列或集合的元素与另一个序列或集合的元素组合而无需任何键选择或任何过滤条件和数量结果序列中存在的元素数量等于两个源序列或集合中元素的乘积。换句话说，我们可以说交叉连接将产生笛卡尔乘积。交叉联接也称为完全联接。在交叉连接中，我们不需要指定连接条件的on关键字。
让我们借助给定的示例来讨论这个概念：
范例1：
// C# program to illustrate the concept
// of the cross join
using System;
using System.Linq;
using System.Collections.Generic;
// Employee details
public class Employee {
public int emp_id
{
get;
set;
}
public string emp_name
{
get;
set;
}
public string emp_lang
{
get;
set;
}
public int dpt_id
{
get;
set;
}
}
// Employee department details
public class Department {
public int dpt_id
{
get;
set;
}
public string emp_dept
{
get;
set;
}
}
class GFG {
// Main method
static public void Main()
{
List emp = new List() {
new Employee() { emp_id = 101, emp_name = "Amit",
emp_lang = "Java", dpt_id = 1 },
new Employee() { emp_id = 102, emp_name = "Mohit",
emp_lang = "C#", dpt_id = 2 },
new Employee() { emp_id = 103, emp_name = "Sona",
emp_lang = "Java", dpt_id = 1 },
new Employee() { emp_id = 104, emp_name = "Lana",
emp_lang = "C++", dpt_id = 3 },
new Employee() { emp_id = 105, emp_name = "Roma",
emp_lang = "C#", dpt_id = 2 },
};
List Dpt = new List() {
new Department() { dpt_id = 1, emp_dept = "Designing" },
new Department() { dpt_id = 2, emp_dept = "Development" },
new Department() { dpt_id = 3, emp_dept = "JE" },
};
// Implementing Cross join using query syntax
var res = from first in emp
from second in Dpt
select new {
Employee_name = first.emp_name,
Department_name = second.emp_dept
};
// Display result
foreach(var val in res)
{
Console.WriteLine(" Employee Name: {0} || Department Name: {1}",
val.Employee_name, val.Department_name);
}
}
}
输出：
Employee Name: Amit || Department Name: Designing
Employee Name: Amit || Department Name: Development
Employee Name: Amit || Department Name: JE
Employee Name: Mohit || Department Name: Designing
Employee Name: Mohit || Department Name: Development
Employee Name: Mohit || Department Name: JE
Employee Name: Sona || Department Name: Designing
Employee Name: Sona || Department Name: Development
Employee Name: Sona || Department Name: JE
Employee Name: Lana || Department Name: Designing
Employee Name: Lana || Department Name: Development
Employee Name: Lana || Department Name: JE
Employee Name: Roma || Department Name: Designing
Employee Name: Roma || Department Name: Development
Employee Name: Roma || Department Name: JE
范例2：
// C# program to illustrate the concept
// of cross join
using System;
using System.Linq;
using System.Collections.Generic;
// Employee details
public class Employee {
public int emp_id
{
get;
set;
}
public string emp_name
{
get;
set;
}
public string emp_lang
{
get;
set;
}
public int dpt_id
{
get;
set;
}
}
// Employee department details
public class Department {
public int dpt_id
{
get;
set;
}
public string emp_dept
{
get;
set;
}
}
class GFG {
// Main method
static public void Main()
{
List emp = new List() {
new Employee() { emp_id = 101, emp_name = "Amit",
emp_lang = "Java", dpt_id = 1 },
new Employee() { emp_id = 102, emp_name = "Mohit",
emp_lang = "C#", dpt_id = 2 },
};
List Dpt = new List() {
new Department() { dpt_id = 1, emp_dept = "Designing" },
new Department() { dpt_id = 2, emp_dept = "Development" },
};
// Implementing Cross join using
// SelectMany method and lambda
// expression
var res_1 = Dpt.SelectMany(e => emp,(x, y) => new {
Department_name = x.emp_dept,
Employee_name = y.emp_name});
// Display result
foreach(var val in res_1)
{
Console.WriteLine(" Department Name: {0} || Employee Name: {1}",
val.Department_name, val.Employee_name);
}
// Implementing Cross join using
// Join method and lambda expression
var res_2 = Dpt.Join(emp, x => true, y => true, (x, y) => new {
Department_name = x.emp_dept,
Employee_name = y.emp_name});
Console.WriteLine();
// Display result
foreach(var val in res_2)
{
Console.WriteLine(" Department Name: {0} || Employee Name: {1}",
val.Department_name, val.Employee_name);
}
}
}
输出：
Department Name: Designing || Employee Name: Amit
Department Name: Designing || Employee Name: Mohit
Department Name: Development || Employee Name: Amit
Department Name: Development || Employee Name: Mohit
Department Name: Designing || Employee Name: Amit
Department Name: Designing || Employee Name: Mohit
Department Name: Development || Employee Name: Amit
Department Name: Development || Employee Name: Mohit