LINQ交叉连接

本文概述

• LINQ Cross Join的语法
• LINQ交叉连接示例

在LINQ中, Cross join将产生项目集合的笛卡尔积。无需任何条件即可连接集合。

在LINQ Cross join中, 左侧集合上的每个元素都将映射到右侧集合上的所有元素。

LINQ Cross Join的语法

这是使用LINQ Cross连接获取集合项的笛卡尔积的语法。

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

根据上述语法, ” objEmp1″集合中的每个元素都将映射到” objDept1″集合中的所有元素。

LINQ交叉连接示例

这是使用LINQ交叉连接获取项目集合的笛卡尔积的示例。

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, 我们没有提及连接集合的任何条件。

输出

这就是我们可以使用LINQ Cross Join获得项目集合的笛卡尔积的方式。