using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; using System.Reflection; class Salary { int _id; int _year; double _salary; public int ID { get { return _id; } set { _id = value; } } public int Year { get { return _year; } set { _year = value; } } public double SalaryPaid { get { return _salary; } set { _salary = value; } } } class Employee { int _id; int _idRole; string _lastName; string _firstName; public int ID { get { return _id; } set { _id = value; } } public int IDRole { get { return _idRole; } set { _idRole = value; } } public string LastName { get { return _lastName; } set { _lastName = value; } } public string FirstName { get { return _firstName; } set { _firstName = value; } } } class Role { int _id; string role; public int ID { get { return _id; } set { _id = value; } } public string Role { get { return role; } set { role = value; } } } public class MainClass { public static void Main() { List<Employee> people = new List<Employee> { new Employee { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"}, new Employee { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"}, new Employee { ID = 3, IDRole = 2, LastName = "G", FirstName = "M"}, new Employee { ID = 4, IDRole = 3, LastName = "C", FirstName = "G"} }; List<Role> roles = new List<Role> { new Role { ID = 1, Role = "Manager" }, new Role { ID = 2, Role = "Developer" } }; List<Salary> salaries = new List<Salary> { new Salary { ID = 1, Year = 2004, SalaryPaid = 10.00 }, new Salary { ID = 1, Year = 2005, SalaryPaid = 15.00 }, new Salary { ID = 1, Year = 2005, SalaryPaid = 15.00 } }; var query = from p in people join s in salaries on p.ID equals s.ID select new { p.FirstName, p.LastName, s.SalaryPaid }; var querySum = from q in query group q by q.LastName into gp select new { LastName = gp.Key, TotalSalary = gp.Sum(q => q.SalaryPaid) }; } }
LINQ
Use join key word
using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; using System.Reflection; class Person { int _id; int _idRole; string _lastName; string _firstName; public int ID { get { return _id; } set { _id = value; } } public int IDRole { get { return _idRole; } set { _idRole = value; } } public string LastName { get { return _lastName; } set { _lastName = value; } } public string FirstName { get { return _firstName; } set { _firstName = value; } } } class Role { int _id; string role; public int ID { get { return _id; } set { _id = value; } } public string Role { get { return role; } set { role = value; } } } class Program { static void Main(string[] args) { List<Person> people = new List<Person> { new Person { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"}, new Person { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"}, new Person { ID = 3, IDRole = 2, LastName = "G", FirstName = "M"}, new Person { ID = 4, IDRole = 3, LastName = "C", FirstName = "G"} }; List<Role> roles = new List<Role> { new Role { ID = 1, Role = "Manager" }, new Role { ID = 2, Role = "Developer" } }; var query = from p in people join r in roles on p.IDRole equals r.ID select p; } }
Join two object lists
using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; using System.Reflection; class Person { int _id; int _idRole; string _lastName; string _firstName; public int ID { get { return _id; } set { _id = value; } } public int IDRole { get { return _idRole; } set { _idRole = value; } } public string LastName { get { return _lastName; } set { _lastName = value; } } public string FirstName { get { return _firstName; } set { _firstName = value; } } } class Role { int _id; string role; public int ID { get { return _id; } set { _id = value; } } public string Role { get { return role; } set { role = value; } } } class Program { static void Main(string[] args) { List<Person> people = new List<Person> { new Person { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"}, new Person { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"}, new Person { ID = 3, IDRole = 2, LastName = "G", FirstName = "M"}, new Person { ID = 4, IDRole = 3, LastName = "C", FirstName = "G"} }; List<Role> roles = new List<Role> { new Role { ID = 1, Role = "Manager" }, new Role { ID = 2, Role = "Developer" } }; var query = from p in people where p.ID == 1 from r in roles where r.ID == p.IDRole select new { p.FirstName, p.LastName, r.Role }; } }
Intersect Operator
using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass { public static void Main() { string[] presidents = {"G", "H", "a", "H", "over", "Jack"}; IEnumerable<string> first = presidents.Take(5); IEnumerable<string> second = presidents.Skip(4); IEnumerable<string> intersect = first.Intersect(second); Console.WriteLine("The count of the array is: " + presidents.Count()); Console.WriteLine("The count of the first sequence is: " + first.Count()); Console.WriteLine("The count of the second sequence is: " + second.Count()); Console.WriteLine("The count of the intersect sequence is: " + intersect.Count()); foreach (string name in intersect) Console.WriteLine(name); } }
prints the first letter of a Product name and the first letter of a Customer name.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
public class MainClass {
public static void Main() {
List
List
var productFirstChars =
from p in products
select p.ProductName[0];
var customerFirstChars =
from c in customers
select c.CompanyName[0];
var commonFirstChars = productFirstChars.Intersect(customerFirstChars);
Console.WriteLine(“Common first letters from Product names and Customer names:”);
foreach (var ch in commonFirstChars) {
Console.WriteLine(ch);
}
}
static List
List
empTree.Add(new Product { ProductName = “A”, Category = “O”, UnitPrice = 12, UnitsInStock = 5, Total = 36, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “B”, Category = “O”, UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “C”, Category = “O”, UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “D”, Category = “O”, UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “E”, Category = “O”, UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “F”, Category = “O”, UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
return empTree;
}
static List
List
empTree.Add(new Product { ProductName = “A”, Category = “O”, UnitPrice = 12, UnitsInStock = 5, Total = 36, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “B”, Category = “O”, UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “C”, Category = “O”, UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “D”, Category = “O”, UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “E”, Category = “O”, UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “F”, Category = “O”, UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
List
l.Add(new Customer { CompanyName = “A”, Region = “R1”, UnitsInStock = 1, Orders = empTree, CustomerId = 0 });
l.Add(new Customer { CompanyName = “B”, Region = “R2”, UnitsInStock = 2, Orders = empTree, CustomerId = 1 });
l.Add(new Customer { CompanyName = “C”, Region = “R3”, UnitsInStock = 3, Orders = empTree, CustomerId = 2 });
l.Add(new Customer { CompanyName = “D”, Region = “R4”, UnitsInStock = 4, Orders = empTree, CustomerId = 3 });
l.Add(new Customer { CompanyName = “E”, Region = “R5”, UnitsInStock = 5, Orders = empTree, CustomerId = 4 });
return l;
}
}
class Customer : IComparable
public string CompanyName { get; set; }
public string Region { get; set; }
public List
public int UnitsInStock { get; set; }
public int CustomerId { get; set; }
public override string ToString() {
return String.Format(“Id: {0}, Name: {1}, Region: {3}”, this.CustomerId, this.CompanyName, this.Region);
}
int IComparable
if (other == null)
return 1;
if (this.CustomerId > other.CustomerId)
return 1;
if (this.CustomerId < other.CustomerId)
return -1;
return 0;
}
}
class Product : IComparable
public string ProductName { get; set; }
public string Category { get; set; }
public int UnitPrice { get; set; }
public int UnitsInStock { get; set; }
public int Total { get; set; }
public DateTime OrderDate { get; set; }
public int Id { get; set; }
public override string ToString() {
return String.Format(“Id: {0}, Name: {1} , Category: {3}”, this.Id, this.ProductName, this.Category);
}
int IComparable
if (other == null)
return 1;
if (this.Id > other.Id)
return 1;
if (this.Id < other.Id) return -1; return 0; } } [/csharp]
prints a list of numbers that are common to two integer arrays.
using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass { public static void Main() { int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 }; int[] numbersB = { 1, 3, 5, 7, 8 }; var commonNumbers = numbersA.Intersect(numbersB); Console.WriteLine("Common numbers shared by both arrays:"); foreach (var n in commonNumbers) { Console.WriteLine(n); } } }
use Linq Intersect to intersect two arrays
using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; public class MainClass{ public static void Main(){ int[] numbers = {1, 1, 2, 3, 3}; int[] numbers2 = {1, 3, 3, 4}; Console.Write(numbers.Intersect(numbers2)); } }