LINQ Cross Join

17 Mar 2025 | 阅读 2 分钟

在 LINQ 中，交叉连接会产生项目集合的笛卡尔积。不需要任何条件来连接集合。

在 LINQ 交叉连接中，左侧集合中的每个元素将映射到右侧集合中的所有元素。

LINQ 交叉连接的语法

以下是使用 LINQ 交叉连接来获取集合项目笛卡尔积的语法。

var result = from e in objEmp1
from d in objDept1
select new
{
    EmployeeName = e.Name,
    DepartmentName = d.DepName
};

从上面的语法可以看出，“objEmp1” 集合中的每个元素将映射到“objDept1” 集合中的所有元素。

LINQ 交叉连接的示例

以下是使用 LINQ 交叉连接来获取项目集合笛卡尔积的示例。

using System;
using System. Collections;
using System.Collections.Generic;
using System. Linq;
using System. Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Programme2
    {
        static void Main(string[] args)
        {
//Create the object of the Department List 'objDept1'  
            List<Department> objDept1 = new List<Department>(){
    //assign the value in the Department
            new Department{DepId=1,DepName="Software"},
            new Department{DepId=2,DepName="Finance"},
            new Department{DepId=3,DepName="Health"}
};
    //Create the object of Employee List 'objEmp1'
            List<Employee> objEmp1 = new List<Employee>()

{
//Insert the value in the Employee list
new Employee { EmpId=1,Name = "Vaishali Tyagi", DeptId=1 },

new Employee { EmpId=2,Name = "Arpita Rai", DeptId=1 },

new Employee { EmpId=3,Name = "Vinay Tyagi", DeptId=2 },

new Employee { EmpId=4,Name = "Sateesh", DeptId =2},

new Employee { EmpId=5,Name = "Madhav"}

};
    /*apply the linq queries to fetch the value from the Employee 
    and Department list and store the value in variable 'result'*/
            var result = from e in objEmp1

                         from d in objDept1
    //Select will fetch the name of the employee and name of the department
                         select new

                         {

                             EmployeeName = e.Name,

                             DepartmentName = d.DepName

                         };
    //foreach loop will print the value of the result with the help of 'WriteLine' funtion
            foreach (var item in result)

            {

                Console.WriteLine(item.EmployeeName + "\t | " + item.DepartmentName);

            }

            Console.ReadLine();

        }

    }
    //Here we create the class named Department and Employee and assignt the variable 
    class Department

    {

        public int DepId { get; set; }

        public string DepName { get; set; }

    }

    class Employee

    {

        public int EmpId { get; set; }

        public string Name { get; set; }

        public int DeptId { get; set; }

    }

}

在上面的示例中，我们没有提到任何连接集合的条件。

输出