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) };
}
}
Month: February 2011
Use Join on
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 = 10000.00 },
new Salary { ID = 1, Year = 2005, SalaryPaid = 15000.00 },
new Salary { ID = 1, Year = 2005, SalaryPaid = 15000.00 }
};
var query = from p in people
join s in salaries on p.ID equals s.ID
where p.ID == 1
select s.SalaryPaid;
Console.Write(query.Min());
Console.Write(query.Max());
}
}
Join Operator
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class Employee {
public int id;
public string firstName;
public string lastName;
public static ArrayList GetEmployeesArrayList() {
ArrayList al = new ArrayList();
al.Add(new Employee { id = 1, firstName = "J", lastName = "R" });
al.Add(new Employee { id = 2, firstName = "W", lastName = "G" });
al.Add(new Employee { id = 3, firstName = "A", lastName = "H" });
al.Add(new Employee { id = 4, firstName = "D", lastName = "L" });
al.Add(new Employee { id = 101, firstName = "K", lastName = "F" });
return (al);
}
public static Employee[] GetEmployeesArray() {
return ((Employee[])GetEmployeesArrayList().ToArray());
}
}
public class EmployeeOptionEntry {
public int id;
public long optionsCount;
public DateTime dateAwarded;
public static EmployeeOptionEntry[] GetEmployeeOptionEntries() {
EmployeeOptionEntry[] empOptions = new EmployeeOptionEntry[] {
new EmployeeOptionEntry {
id = 1,
optionsCount = 2,
dateAwarded = DateTime.Parse("1999/12/31") },
new EmployeeOptionEntry {
id = 101,
optionsCount = 2,
dateAwarded = DateTime.Parse("1998/12/31") }
};
return (empOptions);
}
}
public class MainClass {
public static void Main() {
Employee[] employees = Employee.GetEmployeesArray();
EmployeeOptionEntry[] empOptions = EmployeeOptionEntry.GetEmployeeOptionEntries();
var employeeOptions = employees
.Join(
empOptions,
e => e.id,
o => o.id,
(e, o) => new
{
id = e.id,
name = string.Format("{0} {1}", e.firstName, e.lastName),
options = o.optionsCount
});
foreach (var item in employeeOptions)
Console.WriteLine(item);
}
}
Lambda expression used to declare a delegate
using System;
using System.Linq;
using System.Linq.Expressions;
class Program {
static void Main(string[] args) {
Func
for (int i = 0; i < 10; i++) {
if (isOddDelegate(i))
Console.WriteLine(i + " is odd");
else
Console.WriteLine(i + " is even");
}
}
}
[/csharp]
If your query's lambda expressions reference local variables, these variables are subject to outer variable semantics.
using System;
using System.Collections.Generic;
using System.Linq;
public class MainClass {
public static void Main() {
int[] numbers = { 1, 2 };
int factor = 10;
IEnumerable<int> query = numbers.Select(n => n * factor);
factor = 20;
foreach (int n in query) Console.Write(n + "|");
}
}
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 };
}
}
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]

