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Kesishma
Ikkita to’plamni kesishmasini aniqlash uchun Intersect()
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| bet | 31/53 | | Sana | 30.11.2023 | | Hajmi | 1,39 Mb. | | #108476 |
Bog'liq Dasturiy injiniringKesishma
Ikkita to’plamni kesishmasini aniqlash uchun Intersect() metodidan foydalaniladi:
using (PhoneContext db = new PhoneContext())
{
var phones = db.Phones.Where(p => p.Price < 25000)
.Intersect(db.Phones.Where(p => p.Name.Contains("Samsung")));
foreach (var item in phones)
Console.WriteLine(item.Name);
}
Farq
Agar birinchi to’plamdan ikkinchi to’plamda mavjud bo’lmagan elementlarni aniqlashimiz lozim bo’lsa, Except metodidan foydalanamiz:
using (PhoneContext db = new PhoneContext())
{
var selector1 = db.Phones.Where(p => p.Price > 25000); // Samsung Galaxy S4, Samsung Galaxy S4, iPhone S4
var selector2 = db.Phones.Where(p => p.Name.Contains("Samsung")); // Samsung Galaxy S4, Samsung Galaxy S4
var phones = selector1.Except(selector2); // natija - iPhone S4
foreach (var item in phones)
Console.WriteLine(item.Name);
}
Agregat amallari
Linq to Entities orqali SQL ning ichki funksiyalariga Count, Sum va boshqa maxsus metodlar orqali murojaat qilishimiz mumkin.
Tanlashdagi elementlar soni
Count() metodi orqali tanlashdagi elementlar sonini aniqlash mumkin:
using (PhoneContext db = new PhoneContext())
{
// jami telefon modellari soni
int number1 = db.Phones.Count();
// Samsung qiymatini o’zida saqlagan modellar sonini aniqlaymiz
int number2 = db.Phones.Count(p => p.Name.Contains("Samsung"));
Console.WriteLine(number1);
Console.WriteLine(number2);
}
Minimal, maksimal va o'rta qiymatlar
Minimal, maksimal va o'rta qiymatni aniqlash uchun mos ravishda Min(), Max() va Average() funksiyalardan foydalaniladi. Model bo’yicha minimal, maksimal va o'rta qiymatni aniqlaymiz:
using (PhoneContext db = new PhoneContext())
{
// minimal narx
int minPrice = db.Phones.Min(p => p.Price);
// maksimal narx
int maxPrice = db.Phones.Max(p => p.Price);
// Samsung firmasi telefonlarining o’rtacha narxi
double avgPrice = db.Phones.Where(p => p.Company.Name == "Samsung").Average(p => p.Price);
Console.WriteLine(minPrice);
Console.WriteLine(maxPrice);
Console.WriteLine(avgPrice);
}
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