Введение в LINQ

Составляющие LINQ
Автоматические свойства
Инициализаторы объектов и коллекций
Анонимные типы
Методы расширения
Лямбда-выражения

Автоматические свойства
private string _firstName;
public string firstName
{
get { return _firstName; }
set { _firstName = value; }
}

Автоматические свойства
private string _firstName;
public string firstName
{
get { return _firstName; }
set { _firstName = value; }
}
public string FirstName { get; set; }

Неявно типизированные
локальные переменные
var i = 5;
var s = "Hello";
var d = 1.0;
var numbers = new int[] { 1, 2, 3 };

Правила неявно типизированных локальных переменных
var x; // Ошибка
var y = {1, 2, 3}; // Ошибка
var z = null; // Ошибка
var не может использоваться в полях в области действия класса.
int i = (i = 20); // ОК
var i = (i = 20); // Ошибка
var a = 5, b = 10; // Ошибка
Если тип с именем var находится в области действия, то ключевое слово var будет преобразовано в это имя типа и не будет обрабатываться как часть неявно типизированного объявления локальной переменной.

Инициализаторы объектов
public class Car
{
public string VIN { get; set; }
public string Make { get; set; }
public string Model { get; set; }
public int Year { get; set; }
public string Color { get; set; }
}

Инициализаторы объектов
Car c = new Car();
c.VIN = "ABC123";
c.Make = "Ford";
c.Model = "F-250";
c.Year = 2000;

Инициализаторы объектов
Car c = new Car();
c.VIN = "ABC123";
c.Make = "Ford";
c.Model = "F-250";
c.Year = 2000;
Car c = new Car()
{
VIN = "ABC123",
Make = "Ford",
Model = "F-250",
Year = 2000
};

Инициализаторы коллекций
private List
GetCars()
{
return new List
{
new Car { VIN = "ABC123", Make = "Ford",
Model = "F-250", Year = 2000 },
new Car { VIN = "DEF123", Make = "BMW",
Model = "Z-3", Year = 2005 },
new Car { VIN = "ABC456", Make = "Audi",
Model = "TT", Year = 2008 },
new Car { VIN = "HIJ123", Make = "VW",
Model = "Bug", Year = 1956 },
new Car { VIN = "DEF456", Make = "Ford",
Model = "F-150", Year = 1998 }
};
}

Анонимные типы
var car = new { Make = "VW", Model = "Bug" };

Методы расширения
public static class MyExtensions
{
public static bool IsValidEmailAddress(this string s)
{ Regex regex = new Regex(@"^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$");
return regex.IsMatch(s);
}
}
string s = "
[email protected]
";
bool result = s.IsValidEmailAddress();

Правила методов расширений
Метод расширения и класс, в котором он объявлен, должны быть статическими с модификатором public
Первый параметр определяет, с каким типом оперирует метод, и перед параметром идет модификатор this
Методы расширения не могут получить доступ к закрытым переменным типа, для расширения которого они используются
Методы расширения находятся в области действия, только если пространство имен было явно импортировано в исходный код с помощью директивы using
Методы расширения не могут переопределить методы класса

Анонимные методы
List
cars = GetCars();
List
filtered = new List
();
foreach (Car car in cars)
{
if (car.Year > 2000 && car.Model.StartsWith("F"))
{
filtered.Add(car);
}
}

Анонимные методы
List
cars = GetCars();
List
filtered = new List
();
foreach (Car car in cars)
{
if (FilterYear(car) && FilterModel(car))
{
filtered.Add(car);
}
}
public bool FilterYear(Car car) { return car.Year > 2000; }
public bool FilterModel(Car car) { return car.Model.StartsWith("F"); }

Анонимные методы
public delegate bool FilterPredicate(Car car);
public bool CheckPredicates(Car car, IList
predicates)
{
foreach (FilterPredicate p in predicates)
{
if (!p(car)) { return false; }
}
return true;
}

Анонимные методы
List
cars = GetCars();
List
predicates = new List
();
predicates.Add(delegate(Car car) { return car.Year > 2000; });
predicates.Add(delegate(Car car) { return car.Model.StartsWith("F"); });
List
filtered = new List
();
foreach (Car car in cars)
{
if (CheckPredicates(car, predicates)) { filtered.Add(car); }
}

Анонимные методы
List
cars = GetCars();
List
predicates = new List
();
predicates.Add ((Car car) => car.Year > 2000);
predicates.Add((Car car) => car.Model.StartsWith("F"));
List
filtered = new List
();
foreach (Car car in cars)
{
if (CheckPredicates(car, predicates)) { filtered.Add(car); }
}

Анонимные методы
List
cars = GetCars();
List
predicates = new List
();
predicates.Add (car => car.Year > 2000);
predicates.Add(car => car.Model.StartsWith("F"));
List
filtered = new List
();
foreach (Car car in cars)
{
if (CheckPredicates(car, predicates)) { filtered.Add(car); }
}

Лямбда-выражения
(string s) => { return s.Length; }
(s) => { return s.Length; }
() => {/* statement(s) */ }
(s) => { return s.Length; }
s => { return s.Length; }
(x,y) => { return x < y; }

Архитектура
C#
.NET Language Integrated Query (LINQ)
LINQ
to SQL
LINQ
to Objects
LINQ
to XML
LINQ
to Datasets
LINQ
to Entities
LINQ data source providers
ADO.NET support for LINQ

LINQ-примеры
(Query-синтаксис)
var query = from book in list
where book.Category == ".NET"
orderby book.NumberOfCopies
select new { book.Title, book.Author};

LINQ-примеры
(Query-синтаксис)
var query = from book in list
where book.Category == ".NET"
orderby book.NumberOfCopies
select new { book.Title, book.Author};
Источник данных

LINQ-примеры
(Query-синтаксис)
var query = from book in list
where book.Category == ".NET"
orderby book.NumberOfCopies
select new { book.Title, book.Author};
Источник данных
Ссылка на сущность в
источнике данных

LINQ-примеры
(Query-синтаксис)
var query = from book in list
where book.Category == ".NET"
orderby book.NumberOfCopies
select new { book.Title, book.Author};
Источник данных
Ссылка на сущность в
источнике данных
Фильтрация и
сортировка

LINQ-примеры
(Query-синтаксис)
var query = from book in list
where book.Category == ".NET"
orderby book.NumberOfCopies
select new { book.Title, book.Author};
Источник данных
Ссылка на сущность в
источнике данных
Фильтрация и
сортировка
Преобразование
данных

Синтаксис
var query = from book in list
where book.Category == ".NET"
orderby book.NumberOfCopies
select new { book.Title, book.Author};

Синтаксис
var query = from book in list
where book.Category == ".NET"
orderby book.NumberOfCopies
select new { book.Title, book.Author};
Обязательное начало
запроса

Синтаксис
var query = from book in list
where book.Category == ".NET"
orderby book.NumberOfCopies
select new { book.Title, book.Author};
Обязательное начало
запроса
Обязательный конец
запроса

Синтаксис
var query = from book in list
where book.Category == ".NET"
orderby book.NumberOfCopies
select new { book.Title, book.Author};
Обязательное начало
запроса
Обязательный конец
запроса
В середине
запроса
могут
содержаться
одно или более
условий:
where
orderby
join
let
from
into

Ключевые слова
C# LINQ
ANSI SQL

Отложенное выполение
string[] colors = { "Red", "Brown", "Orange", "Yellow", "Black", "Green", "White", "Violet", "Blue" };
IEnumerable
results = from c in colors
where c.StartsWith("B")
orderby c
select c;
foreach (var color in results)
{
txtLog.AppendText(color + ",");
}
Output: Brown, Black, Blue

Отложенное выполение
string[] colors = { "Red", "Brown", "Orange", "Yellow", "Black", "Green", "White", "Violet", "Blue" };
IEnumerable
results = from c in colors
where c.StartsWith("B")
orderby c
select c;
colors[4] = "Slate";
foreach (var color in results)
{
txtLog.AppendText(color + ",");
}
Output: Brown, Blue

Query Extension Methods
Enumerable static methods
Empty
var numbers = Enumerable.Empty
();
Range
var numbers = Enumerable.Range(1, 5);
Output: 1, 2, 3, 4, 5
Repeat
var numbers = Enumerable.Repeat(10, 5);
Output: 10, 10, 10, 10, 10

Query Extension Methods
All, Any
All
bool result = GetCars().All(c => c.Year > 1960);
Any
bool result = GetCars().Any(c => c.Year <= 1960);

Query Extension Methods AsEnumerable
public class MyStringList : List
{
public IEnumerable
Where(Predicate
filter) {
return this.Select(s => filter(s) ? s.ToUpper() : s);
}
}
var strings = new MyStringList {"orange", "apple", "grape", "pear"};
foreach (var item in strings.Where(s => s.Length == 5))
{
txtLog.Write(item);
}
Output: orange, APPLE, GRAPE, pear

Query Extension Methods AsEnumerable
public class MyStringList : List
{
public IEnumerable
Where(Predicate
filter) {
return this.Select(s => filter(s) ? s.ToUpper() : s);
}
}
var strings = new MyStringList {"orange", "apple", "grape", "pear"};
foreach (var item in strings.AsEnumerable().Where(s => s.Length == 5))
{
txtLog.Write(item);
}
Output: apple, grape

Query Extension Methods
AsQueryable
IEnumerable
strings = new MyStringList {"orange", "apple", "grape", "pear"};
var querable = strings.AsQueryable();
txtLog.WriteLine("Element Type: {0}", querable.ElementType);
txtLog.WriteLine("Expression: {0}", querable.Expression);
txtLog.WriteLine("Provider: {0}", querable.Provider);
Output:
Element Type: System.String
Expression: MyStringList
Provider: MyStringList

Query Extension Methods
ToArray, ToList
int[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };
var evenScores = scores.Where(s => s % 2 == 0).ToList(); // ToArray()
scores[2] = 2;
foreach (var item in evenScores)
{
txtLog.WriteLine(item);
}
Output:
88
56
78
90

Query Extension Methods
ToDictionary, ToLookUp
var cars = GetCars();
var carsByVin = cars.ToDictionary(c => c.VIN);
Car myCar = carsByVin["HIJ123"];
txtLog.WriteLine("Car VIN:{0}, Make:{1}, Model:{2} Year:{3}",
myCar.VIN, myCar.Make, myCar.Model, myCar.Year);
Output:
Car VIN:HIJ123, Make:VW, Model:Bug Year:1956

Query Extension Methods
Cast, OfType
int[] scores = {88, 56, 23, 99, 65, 93, 78, 23, 99, 90};
IEnumerable
objects = scores.Cast
();
object[] items = new object[] {55, "Hello", 22, "Goodbye"};
foreach (var intItem in items.OfType
())
{
txtLog.WriteLine(intItem);
}
Output:
55
22
Слайд 42
Query Extension Methods
Max, Min, Average, Sum, Count
int[] scores = {88, 56, 23,
99, 65, 93, 78, 23, 99, 90};
txtLog.WriteLine("Max: " + scores.Max());
txtLog.WriteLine("Min: " + scores.Min());
txtLog.WriteLine("Average: " + scores.Average());
txtLog.WriteLine("Sum: " + scores.Sum());
txtLog.WriteLine("Count: " + scores.Count());
Output:
Max: 99
Min: 23
Average: 71,4
Sum: 714
Count: 10
Слайд 43
Query Extension Methods
ElementAt, First, Last
int[] scores = {88, 56, 23, 99, 65,
93, 78, 23, 99, 90};
txtLog.WriteLine(scores.ElementAt(4));
txtLog.WriteLine(scores.First());
txtLog.WriteLine(scores.Last());
Output:
65
88
90
Слайд 44
Query Extension Methods
ElementAtOrDefault, FirstOrDefault, LastOrDefault
int[] scores = {};
txtLog.WriteLine(scores.ElementAtOrDefault(4));
txtLog.WriteLine(scores.FirstOrDefault());
txtLog.WriteLine(scores.LastOrDefault());
Output:
0
0
0
Слайд 45
Query Extension Methods
Single, SingleOrDefault
int[] scores = {88, 56, 23, 99, 65, 93,
78, 23, 99, 90};
int score1 = scores.Where(x => x > 50 && x < 60).Single();
int score2 = scores.Where(x => x > 100).SingleOrDefault();
txtLog.WriteLine(score1);
txtLog.WriteLine(score2);
Output:
56
0
Слайд 46
Query Extension Methods
DefaultIfEmpty
List
cars = new List
();
IEnumerable
oneNullCar = cars.DefaultIfEmpty();
foreach (var car
in oneNullCar)
{
txtLog.WriteLine(car == null ? "Null Car" : "Not Null Car");
}
Output: Null Car
Слайд 47
Query Extension Methods
Contains
int[] scores = { 88, 56, 23, 99, 65, 93,
78, 23, 99, 90 };
txtLog.WriteLine(scores.Contains(56));
txtLog.WriteLine(scores.Contains(24));
Output:
True
False
Слайд 48
Query Extension Methods
Distinct
int[] scores = { 88, 56, 23, 99, 65, 93,
78, 23, 99, 90 };
foreach (var score in scores.Distinct())
{
txtLog.Write(score);
}
Output: 88, 56, 23, 99, 65, 93, 78, 90
Слайд 49
Query Extension Methods
Concat
int[] lastYearScores = { 88, 56, 23, 99, 65 };
int[]
thisYearScores = { 93, 78, 23, 99, 90 };
foreach (var item in lastYearScores.Concat(thisYearScores))
{
txtLog.Write(item);
}
Output: 88, 56, 23, 99, 65, 93, 78, 23, 99, 90
Слайд 50
Query Extension Methods
Except
int[] lastYearScores = { 88, 56, 23, 99, 65 };
int[]
thisYearScores = { 93, 78, 23, 99, 90 };
foreach (var item in lastYearScores.Except(thisYearScores))
{
txtLog.WriteLine(item);
}
Output:
88
56
65
Слайд 51
Query Extension Methods
Intersect
int[] lastYearScores = { 88, 56, 23, 99, 65 };
int[]
thisYearScores = { 93, 78, 23, 99, 90 };
foreach (var item in lastYearScores.Intersect(thisYearScores))
{
txtLog.WriteLine(item);
}
Output:
23
99
Слайд 52
Query Extension Methods
Union
int[] lastYearScores = { 88, 56, 23, 99, 65, 56
};
int[] thisYearScores = { 93, 78, 23, 99, 90, 99 };
var allScores = lastYearScores.Union(thisYearScores);
foreach (var item in allScores.OrderBy(s => s))
{
txtLog.WriteLine(item);
}
Output: 23, 56, 65, 78, 88, 90, 93, 99
Слайд 53
Query Extension Methods
Zip
var numbers = Enumerable.Range(1, 1000);
var cars = GetCars();
var zip =
numbers.Zip(cars, (i, c) => new
{
Number = i,
CarMake = c.Make
});
foreach (var it in zip)
{
txtLog.WriteLine("Number:{0} Make:{1}", it.Number, it.CarMake);
}
Output:
Number:1 CarMake:Ford
Number:2 CarMake:BMW
Number:3 CarMake:Audi
Number:4 CarMake:VW
Number:5 CarMake:Ford
Слайд 54
Query Extension Methods
Reverse
int[] scores = { 88, 56, 23, 99, 65, 93,
78, 23, 99, 90 };
foreach (var score in scores.Reverse())
{
txtLog.Write(score);
}
Output: 90, 99, 23, 78, 93, 65, 99, 23, 56, 88
Слайд 55
Query Extension Methods
SequenceEqual
List
lastYearScores = new List
{93, 78, 23, 99, 91};
List
thisYearScores = new List
{93, 78, 23, 99, 90};
txtLog.WriteLine(lastYearScores.SequenceEqual(thisYearScores));
lastYearScores[4] = 90;
txtLog.WriteLine(lastYearScores.SequenceEqual(thisYearScores));
Output:
False
True
Слайд 56
Query Extension Methods
Skip, SkipWhile
int[] scores = { 88, 56, 23, 99, 65,
93, 78, 23, 99, 90 };
foreach (var s in scores.OrderBy(i => i).Skip(9))
{ txtLog.WriteLine(s); }
Output: 99
foreach (var s in scores.OrderBy(i => i).SkipWhile(s => s < 80))
{ txtLog.Write(s); }
Output: 88, 90, 93, 99, 99
foreach (var s in scores.SkipWhile(s => s < 80))
{ txtLog.Write(s); }
Output: 88, 56, 23, 99, 65, 93, 78, 23, 99, 90
Слайд 57
Query Extension Methods
Take, TakeWhile
int[] scores = { 88, 56, 23, 99, 65,
93, 78, 23, 99, 90 };
foreach (var item in scores.OrderBy(i => i).Skip(3).Take(2))
{
txtLog.Write(item);
}
Output: 65, 78
foreach (var item in scores.OrderBy(i => i).TakeWhile(s => s < 80))
{
txtLog.WriteLine(item);
}
Output: 23, 23, 56, 65, 78
Слайд 58
Query Extension Methods
GroupBy
var cars = GetCars();
var query = cars.GroupBy(c => c.Make);
foreach (IGrouping
Car> group in query)
{
txtLog.WriteLine("Key:{0}", group.Key);
foreach (Car c in group)
{ txtLog.WriteLine("Car VIN:{0} Make:{1}", c.VIN, c.Make); }
}
Output:
Key:Ford
Car VIN:ABC123 Make:Ford
Car VIN:DEF456 Make:Ford
Key:BMW
Car VIN:DEF123 Make:BMW
Key:Audi
Car VIN:ABC456 Make:Audi
Key:VW
Car VIN:HIJ123 Make:VW
Слайд 59
Query Extension Methods
OrderBy, OrderByDescending, ThenBy, ThenByDescending
var cars = GetCars().OrderBy(c => c.Make)
.ThenByDescending(c
=> c.Model)
.ThenBy(c => c.Year);
foreach (var item in cars)
{
txtLog.WriteLine("Car VIN:{0} Make:{1} Model:{2} Year:{3}",
item.VIN, item.Make, item.Model, item.Year);
}
Output:
Car VIN:ABC456 Make:Audi Model:TT Year:2008
Car VIN:DEF123 Make:BMW Model:Z-3 Year:2005
Car VIN:ABC123 Make:Ford Model:F-250 Year:2000
Car VIN:DEF456 Make:Ford Model:F-150 Year:1998
Car VIN:HIJ123 Make:VW Model:Bug Year:1956
Слайд 60
Query Extension Methods
Where
var cars = GetCars();
foreach (var myCar in cars.Where(c => c.Make
== "Ford"))
{
txtLog.WriteLine("Car VIN:{0}, Make:{1}, Model:{2} Year:{3}",
myCar.VIN, myCar.Make, myCar.Model, myCar.Year);
}
Output:
Car VIN:ABC123, Make:Ford, Model:F-250 Year:2000
Car VIN:DEF456, Make:Ford, Model:F-150 Year:1998
Слайд 61
Query Extension Methods
Select
var vehicles = new List
>
{
Tuple.Create("123", "VW",
1999),
Tuple.Create("234", "Ford", 2009),
Tuple.Create("567", "Audi", 2005),
Tuple.Create("678", "Ford", 2003),
Tuple.Create("789", "Mazda", 2003),
Tuple.Create("999", "Ford", 1965)
};
Слайд 62
Query Extension Methods
Select
var fordCars = vehicles
.Where(v => v.Item2 == "Ford")
.Select(v
=> new Car
{
VIN = v.Item1,
Make = v.Item2,
Year = v.Item3
});
foreach (var item in fordCars)
{
txtLog.WriteLine("Car VIN:{0} Make:{1} Year:{2}",
item.VIN, item.Make, item.Year);
}
Слайд 63
Query Extension Methods
Select
Output:
Car VIN:234 Make:Ford Year:2009
Car VIN:678 Make:Ford Year:2003
Car VIN:999 Make:Ford
Year:1965
Слайд 64
Query Extension Methods
Select
var fordCars = from v in vehicles
let makeYear =
v.Item2 + " " + v.Item3
where makeYear.StartsWith("Ford")
select new
{
VIN = v.Item1,
MakeYear = makeYear
};
foreach (var item in fordCars)
{
txtLog.WriteLine("Car VIN:{0} MakeYear:{1}",
item.VIN, item.MakeYear);
}
Слайд 65
Query Extension Methods
Select
Output:
Car VIN:234 MakeYear:Ford 2009
Car VIN:678 MakeYear:Ford 2003
Car VIN:999 MakeYear:Ford
1965
Слайд 66
Query Extension Methods
SelectMany
var repairs = new List
>>
{
Tuple.Create("ABC123",
new List
{"Rotate Tires", "Change oil"}),
Tuple.Create("DEF123",
new List
{"Fix Flat", "Wash Vehicle"}),
Tuple.Create("ABC456",
new List
{"Alignment", "Vacuum", "Wax"}),
Tuple.Create("HIJ123",
new List
{"Spark plugs", "Air filter"}),
Tuple.Create("DEF456",
new List
{"Wiper blades", "PVC valve"}),
};
Слайд 67
Query Extension Methods
SelectMany
var query = repairs.SelectMany(t =>
t.Item2.Select(r => new { VIN
= t.Item1, Repair = r }));
foreach (var item in query)
{
txtLog.WriteLine("VIN:{0} Repair:{1}", item.VIN, item.Repair);
}
Слайд 68
Query Extension Methods
SelectMany
Output:
VIN:ABC123 Repair:Rotate Tires
VIN:ABC123 Repair:Change oil
VIN:DEF123 Repair:Fix Flat
VIN:DEF123 Repair:Wash
Vehicle
VIN:ABC456 Repair:Alignment
VIN:ABC456 Repair:Vacuum
VIN:ABC456 Repair:Wax
VIN:HIJ123 Repair:Spark plugs
VIN:HIJ123 Repair:Air filter
VIN:DEF456 Repair:Wiper blades
VIN:DEF456 Repair:PVC valve
Слайд 69
Query Extension Methods
Join
var makes = new string[] { "Audi", "BMW", "Ford", "Mazda",
"VW" };
var cars = GetCars();
var query = makes.Join(cars,
make => make, car => car.Make,
(make, innerCar) => new { Make = make, Car = innerCar });
foreach (var item in query)
{
txtLog.WriteLine("Make: {0}, Car:{1} {2} {3}",
item.Make, item.Car.VIN, item.Car.Make, item.Car.Model);
}
Output:
Make: Audi, Car:ABC456 Audi TT
Make: BMW, Car:DEF123 BMW Z-3
Make: Ford, Car:ABC123 Ford F-250
Make: Ford, Car:DEF456 Ford F-150
Make: VW, Car:HIJ123 VW Bug
Слайд 70
Query Extension Methods
GroupJoin
var makes = new string[] { "Audi", "BMW", "Ford", "Mazda",
"VW" };
var cars = GetCars();
var query = makes.GroupJoin(cars,
make => make, car => car.Make,
(make, innerCars) => new { Make = make, Cars = innerCars });
foreach (var item in query)
{
txtLog.WriteLine("Make: {0}", item.Make);
foreach (var car in item.Cars)
{ txtLog.WriteLine("Car VIN:{0}, Model:{1}", car.VIN, car.Model); }
}
Output:
Make: Audi
Car VIN:ABC456, Model:TT
Make: BMW
Car VIN:DEF123, Model:Z-3
Make: Ford
Car VIN:ABC123, Model:F-250
Car VIN:DEF456, Model:F-150
Слайд 71
LINQ Joins
public class Repair {
public string VIN { get; set; }
public string Desc { get; set; }
public decimal Cost { get; set; }
}
private List
GetRepairs()
{
return new List
{
new Repair {VIN = "ABC123", Desc = "Change Oil", Cost = 29.99m},
new Repair {VIN = "DEF123", Desc = "Rotate Tires", Cost =19.99m},
new Repair {VIN = "HIJ123", Desc = "Replace Brakes", Cost = 200},
new Repair {VIN = "DEF456", Desc = "Alignment", Cost = 30},
new Repair {VIN = "ABC123", Desc = "Fix Flat Tire", Cost = 15},
new Repair {VIN = "DEF123", Desc = "Fix Windshield", Cost =420},
new Repair {VIN = "ABC123", Desc = "Replace Wipers", Cost = 20},
new Repair {VIN = "HIJ123", Desc = "Replace Tires", Cost = 1000},
new Repair {VIN = "DEF456", Desc = "Change Oil", Cost = 30} };
}
Слайд 72
LINQ Joins
Inner join
var cars = GetCars();
var repairs = GetRepairs();
var carsWithRepairs
= from c in cars
join r in repairs
on c.VIN equals r.VIN
orderby c.VIN, r.Cost
select new
{
c.VIN,
c.Make,
r.Desc,
r.Cost
};
foreach (var item in carsWithRepairs)
{
txtLog.WriteLine("Car VIN:{0}, Make:{1}, Description:{2} Cost:{3:C}",
item.VIN, item.Make, item.Desc, item.Cost);
}
Слайд 73
LINQ Joins
Inner join
Output:
Car VIN:ABC123, Make:Ford, Description:Fix Flat Tire Cost:$15.00
Car VIN:ABC123, Make:Ford, Description:Replace
Wipers Cost:$20.00
Car VIN:ABC123, Make:Ford, Description:Change Oil Cost:$29.99
Car VIN:DEF123, Make:BMW, Description:Rotate Tires Cost:$19.99
Car VIN:DEF123, Make:BMW, Description:Fix Windshield Cost:$420.00
Car VIN:DEF456, Make:Ford, Description:Alignment Cost:$30.00
Car VIN:DEF456, Make:Ford, Description:Change Oil Cost:$30.00
Car VIN:HIJ123, Make:VW, Description:Replace Brakes Cost:$200.00
Car VIN:HIJ123, Make:VW, Description:Replace Tires Cost:$1,000.00
Слайд 74
LINQ Joins
Outer join
var carsWithRepairs = from c in cars
join r in
repairs
on c.VIN equals r.VIN into g
from r in g.DefaultIfEmpty()
orderby c.VIN, r == null ? 0 : r.Cost
select new
{
c.VIN,
c.Make,
Desc = r == null ? "***No Repairs***" : r.Desc,
Cost = r == null ? 0 : r.Cost
};
foreach (var item in carsWithRepairs)
{
txtLog.WriteLine("Car VIN:{0}, Make:{1}, Description:{2} Cost:{3:C}",
item.VIN, item.Make, item.Desc, item.Cost);
}
Слайд 75
LINQ Joins
Outer join
Output:
Car VIN:ABC123, Make:Ford, Description:Fix Flat Tire Cost:$15.00
Car VIN:ABC123, Make:Ford, Description:Replace
Wipers Cost:$20.00
Car VIN:ABC123, Make:Ford, Description:Change Oil Cost:$29.99
Car VIN:ABC456, Make:Audi, Description:***No Repairs*** Cost:$0.00
Car VIN:DEF123, Make:BMW, Description:Rotate Tires Cost:$19.99
Car VIN:DEF123, Make:BMW, Description:Fix Windshield Cost:$420.00
Car VIN:DEF456, Make:Ford, Description:Alignment Cost:$30.00
Car VIN:DEF456, Make:Ford, Description:Change Oil Cost:$30.00
Car VIN:HIJ123, Make:VW, Description:Replace Brakes Cost:$200.00
Car VIN:HIJ123, Make:VW, Description:Replace Tires Cost:$1,000.00
Слайд 76
LINQ Joins
Cross join
var cars = GetCars();
var colors = new string[] { "Red",
"Blue", "Green" };
var carsWithRepairs = from car in cars
from color in colors
orderby car.VIN, color
select new
{
car.VIN,
car.Make,
car.Model,
Color = color
};
foreach (var item in carsWithRepairs)
{
txtLog.WriteLine("Car VIN:{0}, Make:{1}, Model:{2} Color:{3}",
item.VIN, item.Make, item.Model, item.Color);
}
Слайд 77
LINQ Joins
Cross join
Output:
Car VIN:ABC123, Make:Ford, Model:F-250 Color:Blue
Car VIN:ABC123, Make:Ford, Model:F-250 Color:Green
Car
VIN:ABC123, Make:Ford, Model:F-250 Color:Red
Car VIN:ABC456, Make:Audi, Model:TT Color:Blue
Car VIN:ABC456, Make:Audi, Model:TT Color:Green
Car VIN:ABC456, Make:Audi, Model:TT Color:Red
Car VIN:DEF123, Make:BMW, Model:Z-3 Color:Blue
Car VIN:DEF123, Make:BMW, Model:Z-3 Color:Green
Car VIN:DEF123, Make:BMW, Model:Z-3 Color:Red
Car VIN:DEF456, Make:Ford, Model:F-150 Color:Blue
Car VIN:DEF456, Make:Ford, Model:F-150 Color:Green
Car VIN:DEF456, Make:Ford, Model:F-150 Color:Red
Car VIN:HIJ123, Make:VW, Model:Bug Color:Blue
Car VIN:HIJ123, Make:VW, Model:Bug Color:Green
Car VIN:HIJ123, Make:VW, Model:Bug Color:Red
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Презентации взяты из открытого доступа или загружены их авторами, администрация сайта не отвечает за достоверность информации в них. Все права принадлежат авторам материалов: \u003Ca href=\"politika-zashchity-avtorskih-prav\"\u003EПолитика защиты авторских прав\u003C\u002Fa\u003E",seo_text:"\u003Cp\u003EСоставляющие LINQ\u003Cbr\u003E\u003Cp\u003EАвтоматические свойства\u003Cbr\u003EИнициализаторы объектов и коллекций\u003Cbr\u003EАнонимные типы\u003Cbr\u003EМетоды расширения\u003Cbr\u003EЛямбда-выражения\u003Cbr\u003E \u003Cp\u003EАвтоматические свойства\u003Cbr\u003E\u003Cp\u003Eprivate string _firstName;\u003Cbr\u003E\u003Cbr\u003Epublic string firstName\u003Cbr\u003E{\u003Cbr\u003E get { return _firstName; }\u003Cbr\u003E set { _firstName = value; }\u003Cbr\u003E}\u003Cbr\u003E\u003Cbr\u003E",file:"Введение-в-LINQ-.pptx",texts:["\u003Cp\u003EВведение в LINQ\u003Cbr\u003E\u003Cp\u003ENatalie Vegerina\u003Cbr\u003ESoftware engineer\u003Cbr\u003EInfostroy Ltd, \u003Cbr\u003EKharkov, Ukraine\u003Cbr\u003E","\u003Cp\u003EСоставляющие LINQ\u003Cbr\u003E\u003Cp\u003EАвтоматические свойства\u003Cbr\u003EИнициализаторы объектов и коллекций\u003Cbr\u003EАнонимные типы\u003Cbr\u003EМетоды расширения\u003Cbr\u003EЛямбда-выражения\u003Cbr\u003E","\u003Cp\u003EАвтоматические свойства\u003Cbr\u003E\u003Cp\u003Eprivate string _firstName;\u003Cbr\u003Epublic string firstName\u003Cbr\u003E{\u003Cbr\u003E get { return _firstName; }\u003Cbr\u003E set { _firstName = value; }\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003EАвтоматические свойства\u003Cbr\u003E\u003Cp\u003Eprivate string _firstName;\u003Cbr\u003Epublic string firstName\u003Cbr\u003E{\u003Cbr\u003E get { return _firstName; }\u003Cbr\u003E set { _firstName = value; }\u003Cbr\u003E}\u003Cbr\u003E\u003Cbr\u003E\u003Cbr\u003Epublic string FirstName { get; set; }\u003Cbr\u003E","\u003Cp\u003EНеявно типизированные \r\nлокальные переменные\u003Cbr\u003E\u003Cp\u003Evar i = 5;\u003Cbr\u003Evar s = \"Hello\";\u003Cbr\u003Evar d = 1.0;\u003Cbr\u003Evar numbers = new int[] { 1, 2, 3 };\u003Cbr\u003E","\u003Cp\u003EПравила неявно типизированных локальных переменных\u003Cbr\u003E\u003Cp\u003E var x; \u002F\u002F Ошибка\u003Cbr\u003E var y = {1, 2, 3}; \u002F\u002F Ошибка\u003Cbr\u003E var z = null; \u002F\u002F Ошибка\u003Cbr\u003E var не может использоваться в полях в области действия класса.\u003Cbr\u003E int i = (i = 20); \u002F\u002F ОК\u003Cbr\u003E var i = (i = 20); \u002F\u002F Ошибка\u003Cbr\u003E var a = 5, b = 10; \u002F\u002F Ошибка\u003Cbr\u003E Если тип с именем var находится в области действия, то ключевое слово var будет преобразовано в это имя типа и не будет обрабатываться как часть неявно типизированного объявления локальной переменной.\u003Cbr\u003E","\u003Cp\u003EИнициализаторы объектов\u003Cbr\u003E\u003Cp\u003Epublic class Car\u003Cbr\u003E{\u003Cbr\u003E public string VIN { get; set; }\u003Cbr\u003E public string Make { get; set; }\u003Cbr\u003E public string Model { get; set; }\u003Cbr\u003E public int Year { get; set; }\u003Cbr\u003E public string Color { get; set; }\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003EИнициализаторы объектов\u003Cbr\u003E\u003Cp\u003ECar c = new Car();\u003Cbr\u003Ec.VIN = \"ABC123\";\u003Cbr\u003Ec.Make = \"Ford\";\u003Cbr\u003Ec.Model = \"F-250\";\u003Cbr\u003Ec.Year = 2000;\u003Cbr\u003E\u003Cbr\u003E\u003Cbr\u003E","\u003Cp\u003EИнициализаторы объектов\u003Cbr\u003E\u003Cp\u003ECar c = new Car();\u003Cbr\u003Ec.VIN = \"ABC123\";\u003Cbr\u003Ec.Make = \"Ford\";\u003Cbr\u003Ec.Model = \"F-250\";\u003Cbr\u003Ec.Year = 2000;\u003Cbr\u003E\u003Cbr\u003E\u003Cbr\u003ECar c = new Car()\u003Cbr\u003E{\u003Cbr\u003E VIN = \"ABC123\",\u003Cbr\u003E Make = \"Ford\",\u003Cbr\u003E Model = \"F-250\",\u003Cbr\u003E Year = 2000\u003Cbr\u003E};\u003Cbr\u003E","\u003Cp\u003EИнициализаторы коллекций\u003Cbr\u003E\u003Cp\u003Eprivate List\u003CCar\u003E GetCars()\u003Cbr\u003E{\u003Cbr\u003E return new List\u003CCar\u003E\u003Cbr\u003E {\u003Cbr\u003E new Car { VIN = \"ABC123\", Make = \"Ford\",\u003Cbr\u003E Model = \"F-250\", Year = 2000 },\u003Cbr\u003E new Car { VIN = \"DEF123\", Make = \"BMW\",\u003Cbr\u003E Model = \"Z-3\", Year = 2005 },\u003Cbr\u003E new Car { VIN = \"ABC456\", Make = \"Audi\",\u003Cbr\u003E Model = \"TT\", Year = 2008 },\u003Cbr\u003E new Car { VIN = \"HIJ123\", Make = \"VW\",\u003Cbr\u003E Model = \"Bug\", Year = 1956 },\u003Cbr\u003E new Car { VIN = \"DEF456\", Make = \"Ford\",\u003Cbr\u003E Model = \"F-150\", Year = 1998 }\u003Cbr\u003E };\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003EАнонимные типы\u003Cbr\u003Evar car = new { Make = \"VW\", Model = \"Bug\" };\u003Cbr\u003E","\u003Cp\u003EМетоды расширения\u003Cbr\u003E\u003Cp\u003Epublic static class MyExtensions\u003Cbr\u003E{\u003Cbr\u003E public static bool IsValidEmailAddress(this string s)\u003Cbr\u003E {\u003Cbr\u003E Regex regex = new Regex(@\"^[\\w-\\.]+@([\\w-]+\\.)+[\\w-]{2,4}$\");\u003Cbr\u003E return regex.IsMatch(s);\u003Cbr\u003E }\u003Cbr\u003E}\u003Cbr\u003E\u003Cbr\u003Estring s = \"[e-mail]\";\u003Cbr\u003Ebool result = s.IsValidEmailAddress();\u003Cbr\u003E","\u003Cp\u003EПравила методов расширений\u003Cbr\u003E\u003Cp\u003EМетод расширения и класс, в котором он объявлен, должны быть статическими с модификатором public\u003Cbr\u003EПервый параметр определяет, с каким типом оперирует метод, и перед параметром идет модификатор this\u003Cbr\u003EМетоды расширения не могут получить доступ к закрытым переменным типа, для расширения которого они используются\u003Cbr\u003EМетоды расширения находятся в области действия, только если пространство имен было явно импортировано в исходный код с помощью директивы using \u003Cbr\u003EМетоды расширения не могут переопределить методы класса\u003Cbr\u003E","\u003Cp\u003EАнонимные методы\u003Cbr\u003E\u003Cp\u003EList\u003CCar\u003E cars = GetCars();\u003Cbr\u003EList\u003CCar\u003E filtered = new List\u003CCar\u003E();\u003Cbr\u003Eforeach (Car car in cars)\u003Cbr\u003E{\u003Cbr\u003E if (car.Year \u003E 2000 && car.Model.StartsWith(\"F\"))\u003Cbr\u003E {\u003Cbr\u003E filtered.Add(car);\u003Cbr\u003E }\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003EАнонимные методы\u003Cbr\u003E\u003Cp\u003EList\u003CCar\u003E cars = GetCars();\u003Cbr\u003EList\u003CCar\u003E filtered = new List\u003CCar\u003E();\u003Cbr\u003Eforeach (Car car in cars)\u003Cbr\u003E{\u003Cbr\u003E if (FilterYear(car) && FilterModel(car))\u003Cbr\u003E {\u003Cbr\u003E filtered.Add(car);\u003Cbr\u003E }\u003Cbr\u003E}\u003Cbr\u003Epublic bool FilterYear(Car car) { return car.Year \u003E 2000; }\u003Cbr\u003Epublic bool FilterModel(Car car) { return car.Model.StartsWith(\"F\"); }\u003Cbr\u003E","\u003Cp\u003EАнонимные методы\u003Cbr\u003E\u003Cp\u003Epublic delegate bool FilterPredicate(Car car);\u003Cbr\u003Epublic bool CheckPredicates(Car car, IList\u003CFilterPredicate\u003E predicates)\u003Cbr\u003E{\u003Cbr\u003E foreach (FilterPredicate p in predicates)\u003Cbr\u003E {\u003Cbr\u003E if (!p(car)) { return false; }\u003Cbr\u003E }\u003Cbr\u003E return true;\u003Cbr\u003E}\u003Cbr\u003E\u003Cbr\u003E","\u003Cp\u003EАнонимные методы\u003Cbr\u003E\u003Cp\u003EList\u003CCar\u003E cars = GetCars();\u003Cbr\u003EList\u003CFilterPredicate\u003E predicates = new List\u003CFilterPredicate\u003E();\u003Cbr\u003Epredicates.Add(delegate(Car car) { return car.Year \u003E 2000; });\u003Cbr\u003Epredicates.Add(delegate(Car car) { return car.Model.StartsWith(\"F\"); });\u003Cbr\u003EList\u003CCar\u003E filtered = new List\u003CCar\u003E();\u003Cbr\u003Eforeach (Car car in cars)\u003Cbr\u003E{\u003Cbr\u003E if (CheckPredicates(car, predicates)) { filtered.Add(car); }\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003EАнонимные методы\u003Cbr\u003E\u003Cp\u003EList\u003CCar\u003E cars = GetCars();\u003Cbr\u003EList\u003CFilterPredicate\u003E predicates = new List\u003CFilterPredicate\u003E();\u003Cbr\u003Epredicates.Add ((Car car) =\u003E car.Year \u003E 2000);\u003Cbr\u003Epredicates.Add((Car car) =\u003E car.Model.StartsWith(\"F\"));\u003Cbr\u003EList\u003CCar\u003E filtered = new List\u003CCar\u003E();\u003Cbr\u003Eforeach (Car car in cars)\u003Cbr\u003E{\u003Cbr\u003E if (CheckPredicates(car, predicates)) { filtered.Add(car); }\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003EАнонимные методы\u003Cbr\u003E\u003Cp\u003EList\u003CCar\u003E cars = GetCars();\u003Cbr\u003EList\u003CFilterPredicate\u003E predicates = new List\u003CFilterPredicate\u003E();\u003Cbr\u003Epredicates.Add (car =\u003E car.Year \u003E 2000);\u003Cbr\u003Epredicates.Add(car =\u003E car.Model.StartsWith(\"F\"));\u003Cbr\u003EList\u003CCar\u003E filtered = new List\u003CCar\u003E();\u003Cbr\u003Eforeach (Car car in cars)\u003Cbr\u003E{\u003Cbr\u003E if (CheckPredicates(car, predicates)) { filtered.Add(car); }\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003EЛямбда-выражения\u003Cbr\u003E\u003Cp\u003E(string s) =\u003E { return s.Length; }\u003Cbr\u003E (s) =\u003E { return s.Length; }\u003Cbr\u003E() =\u003E {\u002F* statement(s) *\u002F }\u003Cbr\u003E(s) =\u003E { return s.Length; }\u003Cbr\u003E\ts =\u003E { return s.Length; }\u003Cbr\u003E(x,y) =\u003E { return x \u003C y; }\u003Cbr\u003E","\u003Cp\u003EАрхитектура\u003Cbr\u003E\u003Cp\u003EC#\u003Cbr\u003E\u003Cp\u003E.NET Language Integrated Query (LINQ)\u003Cbr\u003E\u003Cp\u003ELINQ\r\nto SQL\u003Cbr\u003E\u003Cp\u003ELINQ\r\nto Objects\u003Cbr\u003E\u003Cp\u003ELINQ\r\nto XML\u003Cbr\u003E\u003Cp\u003ELINQ\r\nto Datasets\u003Cbr\u003E\u003Cp\u003ELINQ\r\nto Entities\u003Cbr\u003E\u003Cp\u003ELINQ data source providers\u003Cbr\u003E\u003Cp\u003EADO.NET support for LINQ\u003Cbr\u003E","\u003Cp\u003ELINQ-примеры\r\n(Query-синтаксис)\u003Cbr\u003E\u003Cbr\u003E\t\t\t\tvar query = from book in list\u003Cbr\u003E\t\t\t\twhere book.Category == \".NET\"\u003Cbr\u003E\t\t\t\torderby book.NumberOfCopies\u003Cbr\u003E\t\t\t\tselect new { book.Title, book.Author};\u003Cbr\u003E\u003Cbr\u003E","\u003Cp\u003ELINQ-примеры\r\n(Query-синтаксис)\u003Cbr\u003E\u003Cbr\u003E\t\t\t\t\u003Cbr\u003E\t\t\t\tvar query = from book in list\u003Cbr\u003E\t\t\t\twhere book.Category == \".NET\"\u003Cbr\u003E\t\t\t\torderby book.NumberOfCopies\u003Cbr\u003E\t\t\t\tselect new { book.Title, book.Author};\u003Cbr\u003E\u003Cbr\u003E\u003Cp\u003EИсточник данных\u003Cbr\u003E","\u003Cp\u003ELINQ-примеры\r\n(Query-синтаксис)\u003Cbr\u003E\u003Cbr\u003E\t\t\t\tvar query = from book in list\u003Cbr\u003E\t\t\t\twhere book.Category == \".NET\"\u003Cbr\u003E\t\t\t\torderby book.NumberOfCopies\u003Cbr\u003E\t\t\t\tselect new { book.Title, book.Author};\u003Cbr\u003E\u003Cbr\u003E\u003Cp\u003EИсточник данных\u003Cbr\u003E\u003Cp\u003EСсылка на сущность в\u003Cbr\u003Eисточнике данных\u003Cbr\u003E","\u003Cp\u003ELINQ-примеры\r\n(Query-синтаксис)\u003Cbr\u003E\u003Cbr\u003E\t\t\t\tvar query = from book in list\u003Cbr\u003E\t\t\t\twhere book.Category == \".NET\"\u003Cbr\u003E\t\t\t\torderby book.NumberOfCopies\u003Cbr\u003E\t\t\t\tselect new { book.Title, book.Author};\u003Cbr\u003E\u003Cbr\u003E\u003Cp\u003EИсточник данных\u003Cbr\u003E\u003Cp\u003EСсылка на сущность в\u003Cbr\u003Eисточнике данных\u003Cbr\u003E\u003Cp\u003EФильтрация и \u003Cbr\u003Eсортировка\u003Cbr\u003E","\u003Cp\u003ELINQ-примеры\r\n(Query-синтаксис)\u003Cbr\u003E\u003Cbr\u003E\t\t\t\tvar query = from book in list\u003Cbr\u003E\t\t\t\twhere book.Category == \".NET\"\u003Cbr\u003E\t\t\t\torderby book.NumberOfCopies\u003Cbr\u003E\t\t\t\tselect new { book.Title, book.Author};\u003Cbr\u003E\u003Cbr\u003E\u003Cp\u003EИсточник данных\u003Cbr\u003E\u003Cp\u003EСсылка на сущность в\u003Cbr\u003Eисточнике данных\u003Cbr\u003E\u003Cp\u003EФильтрация и \u003Cbr\u003Eсортировка\u003Cbr\u003E\u003Cp\u003EПреобразование\u003Cbr\u003Eданных\u003Cbr\u003E","\u003Cp\u003EСинтаксис\u003Cbr\u003E\u003Cbr\u003E\t\t\t\tvar query = from book in list\u003Cbr\u003E\t\t\t\twhere book.Category == \".NET\"\u003Cbr\u003E\t\t\t\torderby book.NumberOfCopies\u003Cbr\u003E\t\t\t\tselect new { book.Title, book.Author};\u003Cbr\u003E\u003Cbr\u003E","\u003Cp\u003EСинтаксис\u003Cbr\u003E\u003Cbr\u003E\t\t\t\tvar query = from book in list\u003Cbr\u003E\t\t\t\twhere book.Category == \".NET\"\u003Cbr\u003E\t\t\t\torderby book.NumberOfCopies\u003Cbr\u003E\t\t\t\tselect new { book.Title, book.Author};\u003Cbr\u003E\u003Cbr\u003E\u003Cp\u003EОбязательное начало\u003Cbr\u003Eзапроса\u003Cbr\u003E","\u003Cp\u003EСинтаксис\u003Cbr\u003E\u003Cbr\u003E\t\t\t\tvar query = from book in list\u003Cbr\u003E\t\t\t\twhere book.Category == \".NET\"\u003Cbr\u003E\t\t\t\torderby book.NumberOfCopies\u003Cbr\u003E\t\t\t\tselect new { book.Title, book.Author};\u003Cbr\u003E\u003Cbr\u003E\u003Cp\u003EОбязательное начало\u003Cbr\u003Eзапроса\u003Cbr\u003E\u003Cp\u003EОбязательный конец\u003Cbr\u003Eзапроса\u003Cbr\u003E","\u003Cp\u003EСинтаксис\u003Cbr\u003E\u003Cbr\u003E\t\t\t\tvar query = from book in list\u003Cbr\u003E\t\t\t\twhere book.Category == \".NET\"\u003Cbr\u003E\t\t\t\torderby book.NumberOfCopies\u003Cbr\u003E\t\t\t\tselect new { book.Title, book.Author};\u003Cbr\u003E\u003Cbr\u003E\u003Cp\u003EОбязательное начало\u003Cbr\u003Eзапроса\u003Cbr\u003E\u003Cp\u003EОбязательный конец\u003Cbr\u003Eзапроса\u003Cbr\u003E\u003Cp\u003EВ середине \u003Cbr\u003Eзапроса \u003Cbr\u003Eмогут \u003Cbr\u003Eсодержаться\u003Cbr\u003Eодно или более \u003Cbr\u003Eусловий:\u003Cbr\u003E where\u003Cbr\u003E orderby\u003Cbr\u003E join\u003Cbr\u003E let\u003Cbr\u003E from\u003Cbr\u003E into\u003Cbr\u003E","\u003Cp\u003EКлючевые слова\u003Cbr\u003E\u003Cp\u003EC# LINQ\u003Cbr\u003E\u003Cp\u003EANSI SQL\u003Cbr\u003E","\u003Cp\u003EОтложенное выполение\u003Cbr\u003E\u003Cp\u003Estring[] colors = { \"Red\", \"Brown\", \"Orange\", \"Yellow\", \"Black\", \"Green\", \"White\", \"Violet\", \"Blue\" };\u003Cbr\u003EIEnumerable\u003Cstring\u003E results = from c in colors\u003Cbr\u003E where c.StartsWith(\"B\")\u003Cbr\u003E orderby c\u003Cbr\u003E select c;\u003Cbr\u003Eforeach (var color in results)\u003Cbr\u003E{\u003Cbr\u003E txtLog.AppendText(color + \",\");\u003Cbr\u003E} \u003Cbr\u003EOutput: Brown, Black, Blue\u003Cbr\u003E","\u003Cp\u003EОтложенное выполение\u003Cbr\u003E\u003Cp\u003Estring[] colors = { \"Red\", \"Brown\", \"Orange\", \"Yellow\", \"Black\", \"Green\", \"White\", \"Violet\", \"Blue\" };\u003Cbr\u003EIEnumerable\u003Cstring\u003E results = from c in colors\u003Cbr\u003E where c.StartsWith(\"B\")\u003Cbr\u003E orderby c\u003Cbr\u003E select c;\u003Cbr\u003Ecolors[4] = \"Slate\";\u003Cbr\u003Eforeach (var color in results)\u003Cbr\u003E{\u003Cbr\u003E txtLog.AppendText(color + \",\");\u003Cbr\u003E}\u003Cbr\u003EOutput: Brown, Blue\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nEnumerable static methods\u003Cbr\u003E\u003Cp\u003EEmpty\u003Cbr\u003Evar numbers = Enumerable.Empty\u003Clong\u003E();\u003Cbr\u003ERange\u003Cbr\u003Evar numbers = Enumerable.Range(1, 5); \u003Cbr\u003EOutput: 1, 2, 3, 4, 5 \u003Cbr\u003ERepeat\u003Cbr\u003Evar numbers = Enumerable.Repeat(10, 5);\u003Cbr\u003EOutput: 10, 10, 10, 10, 10\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods \r\nAll, Any\u003Cbr\u003E\u003Cp\u003EAll\u003Cbr\u003Ebool result = GetCars().All(c =\u003E c.Year \u003E 1960);\u003Cbr\u003E\u003Cbr\u003EAny\u003Cbr\u003Ebool result = GetCars().Any(c =\u003E c.Year \u003C= 1960);\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods AsEnumerable\u003Cbr\u003E\u003Cp\u003Epublic class MyStringList : List\u003Cstring\u003E\u003Cbr\u003E{\u003Cbr\u003E public IEnumerable\u003Cstring\u003E Where(Predicate\u003Cstring\u003E filter)\u003Cbr\u003E {\u003Cbr\u003E return this.Select(s =\u003E filter(s) ? s.ToUpper() : s);\u003Cbr\u003E }\u003Cbr\u003E}\u003Cbr\u003Evar strings = new MyStringList {\"orange\", \"apple\", \"grape\", \"pear\"};\u003Cbr\u003Eforeach (var item in strings.Where(s =\u003E s.Length == 5))\u003Cbr\u003E{\u003Cbr\u003E txtLog.Write(item);\u003Cbr\u003E}\u003Cbr\u003EOutput: orange, APPLE, GRAPE, pear\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods AsEnumerable\u003Cbr\u003E\u003Cp\u003Epublic class MyStringList : List\u003Cstring\u003E\u003Cbr\u003E{\u003Cbr\u003E public IEnumerable\u003Cstring\u003E Where(Predicate\u003Cstring\u003E filter)\u003Cbr\u003E {\u003Cbr\u003E return this.Select(s =\u003E filter(s) ? s.ToUpper() : s);\u003Cbr\u003E }\u003Cbr\u003E}\u003Cbr\u003Evar strings = new MyStringList {\"orange\", \"apple\", \"grape\", \"pear\"};\u003Cbr\u003Eforeach (var item in strings.AsEnumerable().Where(s =\u003E s.Length == 5))\u003Cbr\u003E{\u003Cbr\u003E txtLog.Write(item);\u003Cbr\u003E}\u003Cbr\u003EOutput: apple, grape\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nAsQueryable\u003Cbr\u003E\u003Cp\u003EIEnumerable\u003Cstring\u003E strings = new MyStringList {\"orange\", \"apple\", \"grape\", \"pear\"};\u003Cbr\u003Evar querable = strings.AsQueryable();\u003Cbr\u003EtxtLog.WriteLine(\"Element Type: {0}\", querable.ElementType);\u003Cbr\u003EtxtLog.WriteLine(\"Expression: {0}\", querable.Expression);\u003Cbr\u003EtxtLog.WriteLine(\"Provider: {0}\", querable.Provider);\u003Cbr\u003EOutput:\u003Cbr\u003EElement Type: System.String\u003Cbr\u003EExpression: MyStringList\u003Cbr\u003EProvider: MyStringList \u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods \r\nToArray, ToList\u003Cbr\u003E\u003Cp\u003Eint[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };\u003Cbr\u003Evar evenScores = scores.Where(s =\u003E s % 2 == 0).ToList(); \u002F\u002F ToArray()\u003Cbr\u003Escores[2] = 2;\u003Cbr\u003Eforeach (var item in evenScores)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(item);\u003Cbr\u003E}\u003Cbr\u003EOutput: \u003Cbr\u003E88\u003Cbr\u003E56 \u003Cbr\u003E78 \u003Cbr\u003E90\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods \r\nToDictionary, ToLookUp\u003Cbr\u003E\u003Cp\u003Evar cars = GetCars();\u003Cbr\u003Evar carsByVin = cars.ToDictionary(c =\u003E c.VIN);\u003Cbr\u003ECar myCar = carsByVin[\"HIJ123\"];\u003Cbr\u003EtxtLog.WriteLine(\"Car VIN:{0}, Make:{1}, Model:{2} Year:{3}\",\u003Cbr\u003E myCar.VIN, myCar.Make, myCar.Model, myCar.Year);\u003Cbr\u003EOutput: \u003Cbr\u003ECar VIN:HIJ123, Make:VW, Model:Bug Year:1956\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nCast, OfType\u003Cbr\u003E\u003Cp\u003Eint[] scores = {88, 56, 23, 99, 65, 93, 78, 23, 99, 90};\u003Cbr\u003EIEnumerable\u003CObject\u003E objects = scores.Cast\u003Cobject\u003E();\u003Cbr\u003Eobject[] items = new object[] {55, \"Hello\", 22, \"Goodbye\"};\u003Cbr\u003Eforeach (var intItem in items.OfType\u003Cint\u003E())\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(intItem);\u003Cbr\u003E}\u003Cbr\u003EOutput:\u003Cbr\u003E55\u003Cbr\u003E22\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nMax, Min, Average, Sum, Count\u003Cbr\u003E\u003Cp\u003Eint[] scores = {88, 56, 23, 99, 65, 93, 78, 23, 99, 90};\u003Cbr\u003EtxtLog.WriteLine(\"Max: \" + scores.Max());\u003Cbr\u003EtxtLog.WriteLine(\"Min: \" + scores.Min());\u003Cbr\u003EtxtLog.WriteLine(\"Average: \" + scores.Average());\u003Cbr\u003EtxtLog.WriteLine(\"Sum: \" + scores.Sum());\u003Cbr\u003EtxtLog.WriteLine(\"Count: \" + scores.Count());\u003Cbr\u003EOutput:\u003Cbr\u003EMax: 99\u003Cbr\u003EMin: 23\u003Cbr\u003EAverage: 71,4\u003Cbr\u003ESum: 714\u003Cbr\u003ECount: 10\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nElementAt, First, Last\u003Cbr\u003E\u003Cp\u003Eint[] scores = {88, 56, 23, 99, 65, 93, 78, 23, 99, 90};\u003Cbr\u003EtxtLog.WriteLine(scores.ElementAt(4));\u003Cbr\u003EtxtLog.WriteLine(scores.First());\u003Cbr\u003EtxtLog.WriteLine(scores.Last());\u003Cbr\u003E\u003Cbr\u003EOutput: \u003Cbr\u003E65\u003Cbr\u003E88\u003Cbr\u003E90\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nElementAtOrDefault, FirstOrDefault, LastOrDefault\u003Cbr\u003E\u003Cp\u003Eint[] scores = {};\u003Cbr\u003EtxtLog.WriteLine(scores.ElementAtOrDefault(4));\u003Cbr\u003EtxtLog.WriteLine(scores.FirstOrDefault());\u003Cbr\u003EtxtLog.WriteLine(scores.LastOrDefault());\u003Cbr\u003E\u003Cbr\u003EOutput: \u003Cbr\u003E0\u003Cbr\u003E0\u003Cbr\u003E0\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSingle, SingleOrDefault\u003Cbr\u003E\u003Cp\u003Eint[] scores = {88, 56, 23, 99, 65, 93, 78, 23, 99, 90};\u003Cbr\u003Eint score1 = scores.Where(x =\u003E x \u003E 50 && x \u003C 60).Single();\u003Cbr\u003Eint score2 = scores.Where(x =\u003E x \u003E 100).SingleOrDefault();\u003Cbr\u003EtxtLog.WriteLine(score1);\u003Cbr\u003EtxtLog.WriteLine(score2);\u003Cbr\u003E\u003Cbr\u003EOutput: \u003Cbr\u003E56\u003Cbr\u003E0\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nDefaultIfEmpty\u003Cbr\u003E\u003Cp\u003EList\u003CCar\u003E cars = new List\u003CCar\u003E();\u003Cbr\u003EIEnumerable\u003CCar\u003E oneNullCar = cars.DefaultIfEmpty();\u003Cbr\u003Eforeach (var car in oneNullCar)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(car == null ? \"Null Car\" : \"Not Null Car\");\u003Cbr\u003E}\u003Cbr\u003EOutput: Null Car\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nContains\u003Cbr\u003E\u003Cp\u003Eint[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };\u003Cbr\u003EtxtLog.WriteLine(scores.Contains(56));\u003Cbr\u003EtxtLog.WriteLine(scores.Contains(24));\u003Cbr\u003EOutput: \u003Cbr\u003ETrue\u003Cbr\u003EFalse\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nDistinct\u003Cbr\u003E\u003Cp\u003Eint[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };\u003Cbr\u003Eforeach (var score in scores.Distinct())\u003Cbr\u003E{\u003Cbr\u003E txtLog.Write(score);\u003Cbr\u003E}\u003Cbr\u003EOutput: 88, 56, 23, 99, 65, 93, 78, 90\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nConcat\u003Cbr\u003E\u003Cp\u003Eint[] lastYearScores = { 88, 56, 23, 99, 65 };\u003Cbr\u003Eint[] thisYearScores = { 93, 78, 23, 99, 90 };\u003Cbr\u003Eforeach (var item in lastYearScores.Concat(thisYearScores))\u003Cbr\u003E{\u003Cbr\u003E txtLog.Write(item);\u003Cbr\u003E} \u003Cbr\u003EOutput: 88, 56, 23, 99, 65, 93, 78, 23, 99, 90\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nExcept\u003Cbr\u003E\u003Cp\u003Eint[] lastYearScores = { 88, 56, 23, 99, 65 };\u003Cbr\u003Eint[] thisYearScores = { 93, 78, 23, 99, 90 };\u003Cbr\u003Eforeach (var item in lastYearScores.Except(thisYearScores))\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(item);\u003Cbr\u003E}\u003Cbr\u003EOutput: \u003Cbr\u003E88\u003Cbr\u003E56 \u003Cbr\u003E65\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nIntersect\u003Cbr\u003E\u003Cp\u003Eint[] lastYearScores = { 88, 56, 23, 99, 65 };\u003Cbr\u003Eint[] thisYearScores = { 93, 78, 23, 99, 90 };\u003Cbr\u003Eforeach (var item in lastYearScores.Intersect(thisYearScores))\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(item);\u003Cbr\u003E}\u003Cbr\u003EOutput:\u003Cbr\u003E23\u003Cbr\u003E99\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nUnion\u003Cbr\u003E\u003Cp\u003Eint[] lastYearScores = { 88, 56, 23, 99, 65, 56 };\u003Cbr\u003Eint[] thisYearScores = { 93, 78, 23, 99, 90, 99 };\u003Cbr\u003Evar allScores = lastYearScores.Union(thisYearScores);\u003Cbr\u003Eforeach (var item in allScores.OrderBy(s =\u003E s))\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(item);\u003Cbr\u003E}\u003Cbr\u003EOutput: 23, 56, 65, 78, 88, 90, 93, 99\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nZip\u003Cbr\u003E\u003Cp\u003Evar numbers = Enumerable.Range(1, 1000);\u003Cbr\u003Evar cars = GetCars();\u003Cbr\u003Evar zip = numbers.Zip(cars, (i, c) =\u003E new\u003Cbr\u003E {\u003Cbr\u003E Number = i,\u003Cbr\u003E CarMake = c.Make\u003Cbr\u003E });\u003Cbr\u003Eforeach (var it in zip)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Number:{0} Make:{1}\", it.Number, it.CarMake);\u003Cbr\u003E}\u003Cbr\u003EOutput: \u003Cbr\u003ENumber:1 CarMake:Ford\u003Cbr\u003ENumber:2 CarMake:BMW \u003Cbr\u003ENumber:3 CarMake:Audi \u003Cbr\u003ENumber:4 CarMake:VW \u003Cbr\u003ENumber:5 CarMake:Ford\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nReverse\u003Cbr\u003E\u003Cp\u003Eint[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };\u003Cbr\u003Eforeach (var score in scores.Reverse())\u003Cbr\u003E{\u003Cbr\u003E txtLog.Write(score);\u003Cbr\u003E}\u003Cbr\u003EOutput: 90, 99, 23, 78, 93, 65, 99, 23, 56, 88\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSequenceEqual\u003Cbr\u003E\u003Cp\u003EList\u003Cint\u003E lastYearScores = new List\u003Cint\u003E {93, 78, 23, 99, 91};\u003Cbr\u003EList\u003Cint\u003E thisYearScores = new List\u003Cint\u003E {93, 78, 23, 99, 90};\u003Cbr\u003EtxtLog.WriteLine(lastYearScores.SequenceEqual(thisYearScores));\u003Cbr\u003ElastYearScores[4] = 90;\u003Cbr\u003EtxtLog.WriteLine(lastYearScores.SequenceEqual(thisYearScores));\u003Cbr\u003EOutput: \u003Cbr\u003EFalse\u003Cbr\u003ETrue\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSkip, SkipWhile\u003Cbr\u003E\u003Cp\u003Eint[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };\u003Cbr\u003Eforeach (var s in scores.OrderBy(i =\u003E i).Skip(9))\u003Cbr\u003E{ txtLog.WriteLine(s); }\u003Cbr\u003EOutput: 99\u003Cbr\u003Eforeach (var s in scores.OrderBy(i =\u003E i).SkipWhile(s =\u003E s \u003C 80))\u003Cbr\u003E{ txtLog.Write(s); }\u003Cbr\u003EOutput: 88, 90, 93, 99, 99\u003Cbr\u003Eforeach (var s in scores.SkipWhile(s =\u003E s \u003C 80))\u003Cbr\u003E{ txtLog.Write(s); }\u003Cbr\u003EOutput: 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 \u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nTake, TakeWhile\u003Cbr\u003E\u003Cp\u003Eint[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };\u003Cbr\u003Eforeach (var item in scores.OrderBy(i =\u003E i).Skip(3).Take(2))\u003Cbr\u003E{\u003Cbr\u003E txtLog.Write(item);\u003Cbr\u003E}\u003Cbr\u003EOutput: 65, 78\u003Cbr\u003Eforeach (var item in scores.OrderBy(i =\u003E i).TakeWhile(s =\u003E s \u003C 80))\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(item);\u003Cbr\u003E}\u003Cbr\u003EOutput: 23, 23, 56, 65, 78 \u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nGroupBy\u003Cbr\u003E\u003Cp\u003Evar cars = GetCars();\u003Cbr\u003Evar query = cars.GroupBy(c =\u003E c.Make);\u003Cbr\u003Eforeach (IGrouping\u003Cstring, Car\u003E group in query)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Key:{0}\", group.Key);\u003Cbr\u003E foreach (Car c in group)\u003Cbr\u003E { txtLog.WriteLine(\"Car VIN:{0} Make:{1}\", c.VIN, c.Make); }\u003Cbr\u003E}\u003Cbr\u003EOutput: \u003Cbr\u003EKey:Ford\u003Cbr\u003ECar VIN:ABC123 Make:Ford \u003Cbr\u003ECar VIN:DEF456 Make:Ford \u003Cbr\u003EKey:BMW \u003Cbr\u003ECar VIN:DEF123 Make:BMW \u003Cbr\u003EKey:Audi \u003Cbr\u003ECar VIN:ABC456 Make:Audi \u003Cbr\u003EKey:VW \u003Cbr\u003ECar VIN:HIJ123 Make:VW\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nOrderBy, OrderByDescending, ThenBy, ThenByDescending\u003Cbr\u003E\u003Cp\u003Evar cars = GetCars().OrderBy(c =\u003E c.Make)\u003Cbr\u003E .ThenByDescending(c =\u003E c.Model)\u003Cbr\u003E .ThenBy(c =\u003E c.Year);\u003Cbr\u003Eforeach (var item in cars)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Car VIN:{0} Make:{1} Model:{2} Year:{3}\",\u003Cbr\u003E item.VIN, item.Make, item.Model, item.Year);\u003Cbr\u003E}\u003Cbr\u003E\u003Cbr\u003EOutput:\u003Cbr\u003ECar VIN:ABC456 Make:Audi Model:TT Year:2008\u003Cbr\u003ECar VIN:DEF123 Make:BMW Model:Z-3 Year:2005 \u003Cbr\u003ECar VIN:ABC123 Make:Ford Model:F-250 Year:2000 \u003Cbr\u003ECar VIN:DEF456 Make:Ford Model:F-150 Year:1998 \u003Cbr\u003ECar VIN:HIJ123 Make:VW Model:Bug Year:1956\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nWhere\u003Cbr\u003E\u003Cp\u003Evar cars = GetCars();\u003Cbr\u003Eforeach (var myCar in cars.Where(c =\u003E c.Make == \"Ford\"))\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Car VIN:{0}, Make:{1}, Model:{2} Year:{3}\",\u003Cbr\u003E myCar.VIN, myCar.Make, myCar.Model, myCar.Year);\u003Cbr\u003E}\u003Cbr\u003E\u003Cbr\u003EOutput:\u003Cbr\u003ECar VIN:ABC123, Make:Ford, Model:F-250 Year:2000\u003Cbr\u003ECar VIN:DEF456, Make:Ford, Model:F-150 Year:1998\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSelect\u003Cbr\u003E\u003Cp\u003Evar vehicles = new List\u003CTuple\u003Cstring, string, int\u003E\u003E\u003Cbr\u003E {\u003Cbr\u003E Tuple.Create(\"123\", \"VW\", 1999),\u003Cbr\u003E Tuple.Create(\"234\", \"Ford\", 2009),\u003Cbr\u003E Tuple.Create(\"567\", \"Audi\", 2005),\u003Cbr\u003E Tuple.Create(\"678\", \"Ford\", 2003),\u003Cbr\u003E Tuple.Create(\"789\", \"Mazda\", 2003),\u003Cbr\u003E Tuple.Create(\"999\", \"Ford\", 1965)\u003Cbr\u003E };\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSelect\u003Cbr\u003E\u003Cp\u003Evar fordCars = vehicles\u003Cbr\u003E .Where(v =\u003E v.Item2 == \"Ford\")\u003Cbr\u003E .Select(v =\u003E new Car\u003Cbr\u003E {\u003Cbr\u003E VIN = v.Item1,\u003Cbr\u003E Make = v.Item2,\u003Cbr\u003E Year = v.Item3\u003Cbr\u003E });\u003Cbr\u003Eforeach (var item in fordCars)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Car VIN:{0} Make:{1} Year:{2}\",\u003Cbr\u003E item.VIN, item.Make, item.Year);\u003Cbr\u003E} \u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSelect\u003Cbr\u003E\u003Cp\u003EOutput:\u003Cbr\u003ECar VIN:234 Make:Ford Year:2009\u003Cbr\u003ECar VIN:678 Make:Ford Year:2003 \u003Cbr\u003ECar VIN:999 Make:Ford Year:1965\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSelect\u003Cbr\u003E\u003Cp\u003Evar fordCars = from v in vehicles\u003Cbr\u003E let makeYear = v.Item2 + \" \" + v.Item3\u003Cbr\u003E where makeYear.StartsWith(\"Ford\")\u003Cbr\u003E select new\u003Cbr\u003E {\u003Cbr\u003E VIN = v.Item1,\u003Cbr\u003E MakeYear = makeYear\u003Cbr\u003E };\u003Cbr\u003Eforeach (var item in fordCars)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Car VIN:{0} MakeYear:{1}\",\u003Cbr\u003E item.VIN, item.MakeYear);\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSelect\u003Cbr\u003E\u003Cp\u003EOutput:\u003Cbr\u003ECar VIN:234 MakeYear:Ford 2009\u003Cbr\u003ECar VIN:678 MakeYear:Ford 2003 \u003Cbr\u003ECar VIN:999 MakeYear:Ford 1965\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSelectMany\u003Cbr\u003E\u003Cp\u003Evar repairs = new List\u003CTuple\u003Cstring, List\u003Cstring\u003E\u003E\u003E\u003Cbr\u003E {\u003Cbr\u003E Tuple.Create(\"ABC123\",\u003Cbr\u003E new List\u003Cstring\u003E {\"Rotate Tires\", \"Change oil\"}),\u003Cbr\u003E Tuple.Create(\"DEF123\",\u003Cbr\u003E new List\u003Cstring\u003E {\"Fix Flat\", \"Wash Vehicle\"}),\u003Cbr\u003E Tuple.Create(\"ABC456\",\u003Cbr\u003E new List\u003Cstring\u003E {\"Alignment\", \"Vacuum\", \"Wax\"}),\u003Cbr\u003E Tuple.Create(\"HIJ123\",\u003Cbr\u003E new List\u003Cstring\u003E {\"Spark plugs\", \"Air filter\"}),\u003Cbr\u003E Tuple.Create(\"DEF456\",\u003Cbr\u003E new List\u003Cstring\u003E {\"Wiper blades\", \"PVC valve\"}),\u003Cbr\u003E };\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSelectMany\u003Cbr\u003E\u003Cp\u003Evar query = repairs.SelectMany(t =\u003E\u003Cbr\u003E t.Item2.Select(r =\u003E new { VIN = t.Item1, Repair = r }));\u003Cbr\u003Eforeach (var item in query)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"VIN:{0} Repair:{1}\", item.VIN, item.Repair);\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nSelectMany\u003Cbr\u003E\u003Cp\u003EOutput:\u003Cbr\u003EVIN:ABC123 Repair:Rotate Tires\u003Cbr\u003EVIN:ABC123 Repair:Change oil \u003Cbr\u003EVIN:DEF123 Repair:Fix Flat \u003Cbr\u003EVIN:DEF123 Repair:Wash Vehicle \u003Cbr\u003EVIN:ABC456 Repair:Alignment \u003Cbr\u003EVIN:ABC456 Repair:Vacuum \u003Cbr\u003EVIN:ABC456 Repair:Wax \u003Cbr\u003EVIN:HIJ123 Repair:Spark plugs \u003Cbr\u003EVIN:HIJ123 Repair:Air filter \u003Cbr\u003EVIN:DEF456 Repair:Wiper blades \u003Cbr\u003EVIN:DEF456 Repair:PVC valve\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nJoin\u003Cbr\u003E\u003Cp\u003Evar makes = new string[] { \"Audi\", \"BMW\", \"Ford\", \"Mazda\", \"VW\" };\u003Cbr\u003Evar cars = GetCars();\u003Cbr\u003Evar query = makes.Join(cars,\u003Cbr\u003E make =\u003E make, car =\u003E car.Make,\u003Cbr\u003E (make, innerCar) =\u003E new { Make = make, Car = innerCar });\u003Cbr\u003Eforeach (var item in query)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Make: {0}, Car:{1} {2} {3}\",\u003Cbr\u003E item.Make, item.Car.VIN, item.Car.Make, item.Car.Model);\u003Cbr\u003E}\u003Cbr\u003E\u003Cbr\u003EOutput:\u003Cbr\u003EMake: Audi, Car:ABC456 Audi TT\u003Cbr\u003EMake: BMW, Car:DEF123 BMW Z-3 \u003Cbr\u003EMake: Ford, Car:ABC123 Ford F-250 \u003Cbr\u003EMake: Ford, Car:DEF456 Ford F-150 \u003Cbr\u003EMake: VW, Car:HIJ123 VW Bug\u003Cbr\u003E","\u003Cp\u003EQuery Extension Methods\r\nGroupJoin\u003Cbr\u003E\u003Cp\u003Evar makes = new string[] { \"Audi\", \"BMW\", \"Ford\", \"Mazda\", \"VW\" };\u003Cbr\u003Evar cars = GetCars();\u003Cbr\u003Evar query = makes.GroupJoin(cars,\u003Cbr\u003E make =\u003E make, car =\u003E car.Make,\u003Cbr\u003E (make, innerCars) =\u003E new { Make = make, Cars = innerCars });\u003Cbr\u003Eforeach (var item in query)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Make: {0}\", item.Make);\u003Cbr\u003E foreach (var car in item.Cars)\u003Cbr\u003E { txtLog.WriteLine(\"Car VIN:{0}, Model:{1}\", car.VIN, car.Model); }\u003Cbr\u003E}\u003Cbr\u003EOutput:\u003Cbr\u003EMake: Audi\u003Cbr\u003ECar VIN:ABC456, Model:TT \u003Cbr\u003EMake: BMW \u003Cbr\u003ECar VIN:DEF123, Model:Z-3 \u003Cbr\u003EMake: Ford \u003Cbr\u003ECar VIN:ABC123, Model:F-250 \u003Cbr\u003ECar VIN:DEF456, Model:F-150\u003Cbr\u003E","\u003Cp\u003ELINQ Joins\u003Cbr\u003E\u003Cp\u003Epublic class Repair {\u003Cbr\u003E public string VIN { get; set; }\u003Cbr\u003E public string Desc { get; set; }\u003Cbr\u003E public decimal Cost { get; set; }\u003Cbr\u003E}\u003Cbr\u003Eprivate List\u003CRepair\u003E GetRepairs()\u003Cbr\u003E{\u003Cbr\u003E return new List\u003CRepair\u003E { \u003Cbr\u003E new Repair {VIN = \"ABC123\", Desc = \"Change Oil\", Cost = 29.99m},\u003Cbr\u003E new Repair {VIN = \"DEF123\", Desc = \"Rotate Tires\", Cost =19.99m}, \u003Cbr\u003E new Repair {VIN = \"HIJ123\", Desc = \"Replace Brakes\", Cost = 200}, \u003Cbr\u003E new Repair {VIN = \"DEF456\", Desc = \"Alignment\", Cost = 30}, \u003Cbr\u003E new Repair {VIN = \"ABC123\", Desc = \"Fix Flat Tire\", Cost = 15}, \u003Cbr\u003E new Repair {VIN = \"DEF123\", Desc = \"Fix Windshield\", Cost =420}, \u003Cbr\u003E new Repair {VIN = \"ABC123\", Desc = \"Replace Wipers\", Cost = 20}, \u003Cbr\u003E new Repair {VIN = \"HIJ123\", Desc = \"Replace Tires\", Cost = 1000}, \u003Cbr\u003E new Repair {VIN = \"DEF456\", Desc = \"Change Oil\", Cost = 30} };\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003ELINQ Joins\r\nInner join\u003Cbr\u003E\u003Cp\u003Evar cars = GetCars(); \u003Cbr\u003Evar repairs = GetRepairs(); \u003Cbr\u003Evar carsWithRepairs = from c in cars\u003Cbr\u003E join r in repairs\u003Cbr\u003E on c.VIN equals r.VIN\u003Cbr\u003E orderby c.VIN, r.Cost\u003Cbr\u003E select new\u003Cbr\u003E {\u003Cbr\u003E c.VIN,\u003Cbr\u003E c.Make,\u003Cbr\u003E r.Desc,\u003Cbr\u003E r.Cost\u003Cbr\u003E };\u003Cbr\u003Eforeach (var item in carsWithRepairs)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Car VIN:{0}, Make:{1}, Description:{2} Cost:{3:C}\",\u003Cbr\u003E item.VIN, item.Make, item.Desc, item.Cost);\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003ELINQ Joins\r\nInner join\u003Cbr\u003E\u003Cp\u003EOutput:\u003Cbr\u003ECar VIN:ABC123, Make:Ford, Description:Fix Flat Tire Cost:$15.00\u003Cbr\u003ECar VIN:ABC123, Make:Ford, Description:Replace Wipers Cost:$20.00 \u003Cbr\u003ECar VIN:ABC123, Make:Ford, Description:Change Oil Cost:$29.99 \u003Cbr\u003ECar VIN:DEF123, Make:BMW, Description:Rotate Tires Cost:$19.99 \u003Cbr\u003ECar VIN:DEF123, Make:BMW, Description:Fix Windshield Cost:$420.00 \u003Cbr\u003ECar VIN:DEF456, Make:Ford, Description:Alignment Cost:$30.00 \u003Cbr\u003ECar VIN:DEF456, Make:Ford, Description:Change Oil Cost:$30.00 \u003Cbr\u003ECar VIN:HIJ123, Make:VW, Description:Replace Brakes Cost:$200.00 \u003Cbr\u003ECar VIN:HIJ123, Make:VW, Description:Replace Tires Cost:$1,000.00\u003Cbr\u003E","\u003Cp\u003ELINQ Joins\r\nOuter join\u003Cbr\u003E\u003Cp\u003Evar carsWithRepairs = from c in cars\u003Cbr\u003E join r in repairs\u003Cbr\u003E on c.VIN equals r.VIN into g\u003Cbr\u003E from r in g.DefaultIfEmpty()\u003Cbr\u003E orderby c.VIN, r == null ? 0 : r.Cost\u003Cbr\u003E select new\u003Cbr\u003E {\u003Cbr\u003E c.VIN,\u003Cbr\u003E c.Make,\u003Cbr\u003E Desc = r == null ? \"***No Repairs***\" : r.Desc,\u003Cbr\u003E Cost = r == null ? 0 : r.Cost\u003Cbr\u003E };\u003Cbr\u003Eforeach (var item in carsWithRepairs)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Car VIN:{0}, Make:{1}, Description:{2} Cost:{3:C}\",\u003Cbr\u003E item.VIN, item.Make, item.Desc, item.Cost);\u003Cbr\u003E}\u003Cbr\u003E","\u003Cp\u003ELINQ Joins\r\nOuter join\u003Cbr\u003E\u003Cp\u003EOutput:\u003Cbr\u003ECar VIN:ABC123, Make:Ford, Description:Fix Flat Tire Cost:$15.00\u003Cbr\u003ECar VIN:ABC123, Make:Ford, Description:Replace Wipers Cost:$20.00 \u003Cbr\u003ECar VIN:ABC123, Make:Ford, Description:Change Oil Cost:$29.99 \u003Cbr\u003ECar VIN:ABC456, Make:Audi, Description:***No Repairs*** Cost:$0.00 \u003Cbr\u003ECar VIN:DEF123, Make:BMW, Description:Rotate Tires Cost:$19.99 \u003Cbr\u003ECar VIN:DEF123, Make:BMW, Description:Fix Windshield Cost:$420.00 \u003Cbr\u003ECar VIN:DEF456, Make:Ford, Description:Alignment Cost:$30.00 \u003Cbr\u003ECar VIN:DEF456, Make:Ford, Description:Change Oil Cost:$30.00 \u003Cbr\u003ECar VIN:HIJ123, Make:VW, Description:Replace Brakes Cost:$200.00 \u003Cbr\u003ECar VIN:HIJ123, Make:VW, Description:Replace Tires Cost:$1,000.00\u003Cbr\u003E","\u003Cp\u003ELINQ Joins\r\nCross join\u003Cbr\u003E\u003Cp\u003Evar cars = GetCars();\u003Cbr\u003Evar colors = new string[] { \"Red\", \"Blue\", \"Green\" };\u003Cbr\u003Evar carsWithRepairs = from car in cars\u003Cbr\u003E from color in colors\u003Cbr\u003E orderby car.VIN, color\u003Cbr\u003E select new\u003Cbr\u003E {\u003Cbr\u003E car.VIN,\u003Cbr\u003E car.Make,\u003Cbr\u003E car.Model,\u003Cbr\u003E Color = color\u003Cbr\u003E };\u003Cbr\u003Eforeach (var item in carsWithRepairs)\u003Cbr\u003E{\u003Cbr\u003E txtLog.WriteLine(\"Car VIN:{0}, Make:{1}, Model:{2} Color:{3}\",\u003Cbr\u003E \t item.VIN, item.Make, item.Model, item.Color);\u003Cbr\u003E} \u003Cbr\u003E","\u003Cp\u003ELINQ Joins\r\nCross join\u003Cbr\u003E\u003Cp\u003EOutput:\u003Cbr\u003ECar VIN:ABC123, Make:Ford, Model:F-250 Color:Blue\u003Cbr\u003ECar VIN:ABC123, Make:Ford, Model:F-250 Color:Green \u003Cbr\u003ECar VIN:ABC123, Make:Ford, Model:F-250 Color:Red \u003Cbr\u003ECar VIN:ABC456, Make:Audi, Model:TT Color:Blue \u003Cbr\u003ECar VIN:ABC456, Make:Audi, Model:TT Color:Green \u003Cbr\u003ECar VIN:ABC456, Make:Audi, Model:TT Color:Red \u003Cbr\u003ECar VIN:DEF123, Make:BMW, Model:Z-3 Color:Blue \u003Cbr\u003ECar VIN:DEF123, Make:BMW, Model:Z-3 Color:Green\u003Cbr\u003ECar VIN:DEF123, Make:BMW, Model:Z-3 Color:Red \u003Cbr\u003ECar VIN:DEF456, Make:Ford, Model:F-150 Color:Blue \u003Cbr\u003ECar VIN:DEF456, Make:Ford, Model:F-150 Color:Green \u003Cbr\u003ECar VIN:DEF456, Make:Ford, Model:F-150 Color:Red \u003Cbr\u003ECar VIN:HIJ123, Make:VW, Model:Bug Color:Blue \u003Cbr\u003ECar VIN:HIJ123, Make:VW, Model:Bug Color:Green \u003Cbr\u003ECar VIN:HIJ123, Make:VW, Model:Bug Color:Red \u003Cbr\u003E","\u003Cp\u003EЛитература\u003Cbr\u003E\u003Cp\u003EGlenn Johnson - Exam 70-516: TS: Accessing Data with Microsoft .NET Framework 4\u003Cbr\u003EMike Liu - WCF 4.0 Multi-tier Services Development with LINQ to Entities\u003Cbr\u003EMSDN\u003Cbr\u003E"],href:"\u002Fprezentacii-na-razlichnye-temy\u002Fvvedenie-v-linq",href_category:"\u002Fprezentacii-na-razlichnye-temy",date:1613062257,related:[{id:379802,name:"Защитные сооружения гражданской обороны ",href:"\u002Fprezentacii-na-razlichnye-temy\u002Fzashhitnye-sooruzheniya-grazhdanskoj-oborony",jpg:"jpg\u002F379802"},{id:942822,name:"Unit 2a translation",href:"\u002Fprezentacii-na-razlichnye-temy\u002Funit-2a-translation-1",jpg:"jpg\u002F942822"},{id:1064091,name:"Натюрморт в графике",href:"\u002Fprezentacii-na-razlichnye-temy\u002Fnatyurmort-v-grafike-18",jpg:"jpg\u002F1064091"},{id:870160,name:"Художественные стили. 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Query Extension Methods
Max, Min, Average, Sum, Count
int[] scores = {88, 56, 23, 99, 65, 93, 78, 23, 99, 90};
txtLog.WriteLine("Max: " + scores.Max());
txtLog.WriteLine("Min: " + scores.Min());
txtLog.WriteLine("Average: " + scores.Average());
txtLog.WriteLine("Sum: " + scores.Sum());
txtLog.WriteLine("Count: " + scores.Count());
Output:
Max: 99
Min: 23
Average: 71,4
Sum: 714
Count: 10

Query Extension Methods
ElementAt, First, Last
int[] scores = {88, 56, 23, 99, 65, 93, 78, 23, 99, 90};
txtLog.WriteLine(scores.ElementAt(4));
txtLog.WriteLine(scores.First());
txtLog.WriteLine(scores.Last());
Output:
65
88
90

Query Extension Methods
ElementAtOrDefault, FirstOrDefault, LastOrDefault
int[] scores = {};
txtLog.WriteLine(scores.ElementAtOrDefault(4));
txtLog.WriteLine(scores.FirstOrDefault());
txtLog.WriteLine(scores.LastOrDefault());
Output:
0
0
0

Query Extension Methods
Single, SingleOrDefault
int[] scores = {88, 56, 23, 99, 65, 93, 78, 23, 99, 90};
int score1 = scores.Where(x => x > 50 && x < 60).Single();
int score2 = scores.Where(x => x > 100).SingleOrDefault();
txtLog.WriteLine(score1);
txtLog.WriteLine(score2);
Output:
56
0

Query Extension Methods
DefaultIfEmpty
List
cars = new List
();
IEnumerable
oneNullCar = cars.DefaultIfEmpty();
foreach (var car in oneNullCar)
{
txtLog.WriteLine(car == null ? "Null Car" : "Not Null Car");
}
Output: Null Car

Query Extension Methods
Contains
int[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };
txtLog.WriteLine(scores.Contains(56));
txtLog.WriteLine(scores.Contains(24));
Output:
True
False

Query Extension Methods
Distinct
int[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };
foreach (var score in scores.Distinct())
{
txtLog.Write(score);
}
Output: 88, 56, 23, 99, 65, 93, 78, 90

Query Extension Methods
Concat
int[] lastYearScores = { 88, 56, 23, 99, 65 };
int[] thisYearScores = { 93, 78, 23, 99, 90 };
foreach (var item in lastYearScores.Concat(thisYearScores))
{
txtLog.Write(item);
}
Output: 88, 56, 23, 99, 65, 93, 78, 23, 99, 90

Query Extension Methods
Except
int[] lastYearScores = { 88, 56, 23, 99, 65 };
int[] thisYearScores = { 93, 78, 23, 99, 90 };
foreach (var item in lastYearScores.Except(thisYearScores))
{
txtLog.WriteLine(item);
}
Output:
88
56
65

Query Extension Methods
Intersect
int[] lastYearScores = { 88, 56, 23, 99, 65 };
int[] thisYearScores = { 93, 78, 23, 99, 90 };
foreach (var item in lastYearScores.Intersect(thisYearScores))
{
txtLog.WriteLine(item);
}
Output:
23
99

Query Extension Methods
Union
int[] lastYearScores = { 88, 56, 23, 99, 65, 56 };
int[] thisYearScores = { 93, 78, 23, 99, 90, 99 };
var allScores = lastYearScores.Union(thisYearScores);
foreach (var item in allScores.OrderBy(s => s))
{
txtLog.WriteLine(item);
}
Output: 23, 56, 65, 78, 88, 90, 93, 99

Query Extension Methods
Zip
var numbers = Enumerable.Range(1, 1000);
var cars = GetCars();
var zip = numbers.Zip(cars, (i, c) => new
{
Number = i,
CarMake = c.Make
});
foreach (var it in zip)
{
txtLog.WriteLine("Number:{0} Make:{1}", it.Number, it.CarMake);
}
Output:
Number:1 CarMake:Ford
Number:2 CarMake:BMW
Number:3 CarMake:Audi
Number:4 CarMake:VW
Number:5 CarMake:Ford

Query Extension Methods
Reverse
int[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };
foreach (var score in scores.Reverse())
{
txtLog.Write(score);
}
Output: 90, 99, 23, 78, 93, 65, 99, 23, 56, 88

Query Extension Methods
SequenceEqual
List
lastYearScores = new List
{93, 78, 23, 99, 91};
List thisYearScores = new List
{93, 78, 23, 99, 90};
txtLog.WriteLine(lastYearScores.SequenceEqual(thisYearScores));
lastYearScores[4] = 90;
txtLog.WriteLine(lastYearScores.SequenceEqual(thisYearScores));
Output:
False
True

Query Extension Methods
Skip, SkipWhile
int[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };
foreach (var s in scores.OrderBy(i => i).Skip(9))
{ txtLog.WriteLine(s); }
Output: 99
foreach (var s in scores.OrderBy(i => i).SkipWhile(s => s < 80))
{ txtLog.Write(s); }
Output: 88, 90, 93, 99, 99
foreach (var s in scores.SkipWhile(s => s < 80))
{ txtLog.Write(s); }
Output: 88, 56, 23, 99, 65, 93, 78, 23, 99, 90

Query Extension Methods
Take, TakeWhile
int[] scores = { 88, 56, 23, 99, 65, 93, 78, 23, 99, 90 };
foreach (var item in scores.OrderBy(i => i).Skip(3).Take(2))
{
txtLog.Write(item);
}
Output: 65, 78
foreach (var item in scores.OrderBy(i => i).TakeWhile(s => s < 80))
{
txtLog.WriteLine(item);
}
Output: 23, 23, 56, 65, 78

Query Extension Methods
GroupBy
var cars = GetCars();
var query = cars.GroupBy(c => c.Make);
foreach (IGrouping Car> group in query)
{
txtLog.WriteLine("Key:{0}", group.Key);
foreach (Car c in group)
{ txtLog.WriteLine("Car VIN:{0} Make:{1}", c.VIN, c.Make); }
}
Output:
Key:Ford
Car VIN:ABC123 Make:Ford
Car VIN:DEF456 Make:Ford
Key:BMW
Car VIN:DEF123 Make:BMW
Key:Audi
Car VIN:ABC456 Make:Audi
Key:VW
Car VIN:HIJ123 Make:VW

Query Extension Methods
OrderBy, OrderByDescending, ThenBy, ThenByDescending
var cars = GetCars().OrderBy(c => c.Make)
.ThenByDescending(c => c.Model)
.ThenBy(c => c.Year);
foreach (var item in cars)
{
txtLog.WriteLine("Car VIN:{0} Make:{1} Model:{2} Year:{3}",
item.VIN, item.Make, item.Model, item.Year);
}
Output:
Car VIN:ABC456 Make:Audi Model:TT Year:2008
Car VIN:DEF123 Make:BMW Model:Z-3 Year:2005
Car VIN:ABC123 Make:Ford Model:F-250 Year:2000
Car VIN:DEF456 Make:Ford Model:F-150 Year:1998
Car VIN:HIJ123 Make:VW Model:Bug Year:1956

Query Extension Methods
Where
var cars = GetCars();
foreach (var myCar in cars.Where(c => c.Make == "Ford"))
{
txtLog.WriteLine("Car VIN:{0}, Make:{1}, Model:{2} Year:{3}",
myCar.VIN, myCar.Make, myCar.Model, myCar.Year);
}
Output:
Car VIN:ABC123, Make:Ford, Model:F-250 Year:2000
Car VIN:DEF456, Make:Ford, Model:F-150 Year:1998

Query Extension Methods
Select
var vehicles = new List
>
{
Tuple.Create("123", "VW", 1999),
Tuple.Create("234", "Ford", 2009),
Tuple.Create("567", "Audi", 2005),
Tuple.Create("678", "Ford", 2003),
Tuple.Create("789", "Mazda", 2003),
Tuple.Create("999", "Ford", 1965)
};

Query Extension Methods
Select
var fordCars = vehicles
.Where(v => v.Item2 == "Ford")
.Select(v => new Car
{
VIN = v.Item1,
Make = v.Item2,
Year = v.Item3
});
foreach (var item in fordCars)
{
txtLog.WriteLine("Car VIN:{0} Make:{1} Year:{2}",
item.VIN, item.Make, item.Year);
}

Query Extension Methods
Select
Output:
Car VIN:234 Make:Ford Year:2009
Car VIN:678 Make:Ford Year:2003
Car VIN:999 Make:Ford Year:1965

Query Extension Methods
Select
var fordCars = from v in vehicles
let makeYear = v.Item2 + " " + v.Item3
where makeYear.StartsWith("Ford")
select new
{
VIN = v.Item1,
MakeYear = makeYear
};
foreach (var item in fordCars)
{
txtLog.WriteLine("Car VIN:{0} MakeYear:{1}",
item.VIN, item.MakeYear);
}

Query Extension Methods
Select
Output:
Car VIN:234 MakeYear:Ford 2009
Car VIN:678 MakeYear:Ford 2003
Car VIN:999 MakeYear:Ford 1965

Query Extension Methods
SelectMany
var repairs = new List
>>
{
Tuple.Create("ABC123",
new List {"Rotate Tires", "Change oil"}),
Tuple.Create("DEF123",
new List
{"Fix Flat", "Wash Vehicle"}),
Tuple.Create("ABC456",
new List
{"Alignment", "Vacuum", "Wax"}),
Tuple.Create("HIJ123",
new List
{"Spark plugs", "Air filter"}),
Tuple.Create("DEF456",
new List
{"Wiper blades", "PVC valve"}),
};

Query Extension Methods
SelectMany
var query = repairs.SelectMany(t =>
t.Item2.Select(r => new { VIN = t.Item1, Repair = r }));
foreach (var item in query)
{
txtLog.WriteLine("VIN:{0} Repair:{1}", item.VIN, item.Repair);
}

Query Extension Methods
SelectMany
Output:
VIN:ABC123 Repair:Rotate Tires
VIN:ABC123 Repair:Change oil
VIN:DEF123 Repair:Fix Flat
VIN:DEF123 Repair:Wash Vehicle
VIN:ABC456 Repair:Alignment
VIN:ABC456 Repair:Vacuum
VIN:ABC456 Repair:Wax
VIN:HIJ123 Repair:Spark plugs
VIN:HIJ123 Repair:Air filter
VIN:DEF456 Repair:Wiper blades
VIN:DEF456 Repair:PVC valve

Query Extension Methods
Join
var makes = new string[] { "Audi", "BMW", "Ford", "Mazda", "VW" };
var cars = GetCars();
var query = makes.Join(cars,
make => make, car => car.Make,
(make, innerCar) => new { Make = make, Car = innerCar });
foreach (var item in query)
{
txtLog.WriteLine("Make: {0}, Car:{1} {2} {3}",
item.Make, item.Car.VIN, item.Car.Make, item.Car.Model);
}
Output:
Make: Audi, Car:ABC456 Audi TT
Make: BMW, Car:DEF123 BMW Z-3
Make: Ford, Car:ABC123 Ford F-250
Make: Ford, Car:DEF456 Ford F-150
Make: VW, Car:HIJ123 VW Bug

Query Extension Methods
GroupJoin
var makes = new string[] { "Audi", "BMW", "Ford", "Mazda", "VW" };
var cars = GetCars();
var query = makes.GroupJoin(cars,
make => make, car => car.Make,
(make, innerCars) => new { Make = make, Cars = innerCars });
foreach (var item in query)
{
txtLog.WriteLine("Make: {0}", item.Make);
foreach (var car in item.Cars)
{ txtLog.WriteLine("Car VIN:{0}, Model:{1}", car.VIN, car.Model); }
}
Output:
Make: Audi
Car VIN:ABC456, Model:TT
Make: BMW
Car VIN:DEF123, Model:Z-3
Make: Ford
Car VIN:ABC123, Model:F-250
Car VIN:DEF456, Model:F-150

LINQ Joins
public class Repair {
public string VIN { get; set; } public string Desc { get; set; }
public decimal Cost { get; set; }
}
private List
GetRepairs()
{
return new List
{
new Repair {VIN = "ABC123", Desc = "Change Oil", Cost = 29.99m},
new Repair {VIN = "DEF123", Desc = "Rotate Tires", Cost =19.99m},
new Repair {VIN = "HIJ123", Desc = "Replace Brakes", Cost = 200},
new Repair {VIN = "DEF456", Desc = "Alignment", Cost = 30},
new Repair {VIN = "ABC123", Desc = "Fix Flat Tire", Cost = 15},
new Repair {VIN = "DEF123", Desc = "Fix Windshield", Cost =420},
new Repair {VIN = "ABC123", Desc = "Replace Wipers", Cost = 20},
new Repair {VIN = "HIJ123", Desc = "Replace Tires", Cost = 1000},
new Repair {VIN = "DEF456", Desc = "Change Oil", Cost = 30} };
}

LINQ Joins
Inner join
var cars = GetCars();
var repairs = GetRepairs();
var carsWithRepairs = from c in cars
join r in repairs
on c.VIN equals r.VIN
orderby c.VIN, r.Cost
select new
{
c.VIN,
c.Make,
r.Desc,
r.Cost
};
foreach (var item in carsWithRepairs)
{
txtLog.WriteLine("Car VIN:{0}, Make:{1}, Description:{2} Cost:{3:C}",
item.VIN, item.Make, item.Desc, item.Cost);
}

LINQ Joins
Inner join
Output:
Car VIN:ABC123, Make:Ford, Description:Fix Flat Tire Cost:$15.00
Car VIN:ABC123, Make:Ford, Description:Replace Wipers Cost:$20.00
Car VIN:ABC123, Make:Ford, Description:Change Oil Cost:$29.99
Car VIN:DEF123, Make:BMW, Description:Rotate Tires Cost:$19.99
Car VIN:DEF123, Make:BMW, Description:Fix Windshield Cost:$420.00
Car VIN:DEF456, Make:Ford, Description:Alignment Cost:$30.00
Car VIN:DEF456, Make:Ford, Description:Change Oil Cost:$30.00
Car VIN:HIJ123, Make:VW, Description:Replace Brakes Cost:$200.00
Car VIN:HIJ123, Make:VW, Description:Replace Tires Cost:$1,000.00

LINQ Joins
Outer join
var carsWithRepairs = from c in cars
join r in repairs
on c.VIN equals r.VIN into g
from r in g.DefaultIfEmpty()
orderby c.VIN, r == null ? 0 : r.Cost
select new
{
c.VIN,
c.Make,
Desc = r == null ? "***No Repairs***" : r.Desc,
Cost = r == null ? 0 : r.Cost
};
foreach (var item in carsWithRepairs)
{
txtLog.WriteLine("Car VIN:{0}, Make:{1}, Description:{2} Cost:{3:C}",
item.VIN, item.Make, item.Desc, item.Cost);
}

LINQ Joins
Outer join
Output:
Car VIN:ABC123, Make:Ford, Description:Fix Flat Tire Cost:$15.00
Car VIN:ABC123, Make:Ford, Description:Replace Wipers Cost:$20.00
Car VIN:ABC123, Make:Ford, Description:Change Oil Cost:$29.99
Car VIN:ABC456, Make:Audi, Description:***No Repairs*** Cost:$0.00
Car VIN:DEF123, Make:BMW, Description:Rotate Tires Cost:$19.99
Car VIN:DEF123, Make:BMW, Description:Fix Windshield Cost:$420.00
Car VIN:DEF456, Make:Ford, Description:Alignment Cost:$30.00
Car VIN:DEF456, Make:Ford, Description:Change Oil Cost:$30.00
Car VIN:HIJ123, Make:VW, Description:Replace Brakes Cost:$200.00
Car VIN:HIJ123, Make:VW, Description:Replace Tires Cost:$1,000.00

LINQ Joins
Cross join
var cars = GetCars();
var colors = new string[] { "Red", "Blue", "Green" };
var carsWithRepairs = from car in cars
from color in colors
orderby car.VIN, color
select new
{
car.VIN,
car.Make,
car.Model,
Color = color
};
foreach (var item in carsWithRepairs)
{
txtLog.WriteLine("Car VIN:{0}, Make:{1}, Model:{2} Color:{3}",
item.VIN, item.Make, item.Model, item.Color);
}

LINQ Joins
Cross join
Output:
Car VIN:ABC123, Make:Ford, Model:F-250 Color:Blue
Car VIN:ABC123, Make:Ford, Model:F-250 Color:Green
Car VIN:ABC123, Make:Ford, Model:F-250 Color:Red
Car VIN:ABC456, Make:Audi, Model:TT Color:Blue
Car VIN:ABC456, Make:Audi, Model:TT Color:Green
Car VIN:ABC456, Make:Audi, Model:TT Color:Red
Car VIN:DEF123, Make:BMW, Model:Z-3 Color:Blue
Car VIN:DEF123, Make:BMW, Model:Z-3 Color:Green
Car VIN:DEF123, Make:BMW, Model:Z-3 Color:Red
Car VIN:DEF456, Make:Ford, Model:F-150 Color:Blue
Car VIN:DEF456, Make:Ford, Model:F-150 Color:Green
Car VIN:DEF456, Make:Ford, Model:F-150 Color:Red
Car VIN:HIJ123, Make:VW, Model:Bug Color:Blue
Car VIN:HIJ123, Make:VW, Model:Bug Color:Green
Car VIN:HIJ123, Make:VW, Model:Bug Color:Red