static void Main(string[] args)
{
//Language Integrate Query (LINQ)
//a query on the string array such that you have all the names that contain 'u'
string[] names = new string[] { "Niranjan", "Guru", "Arun" };
var result = (from n in names
where n.Contains("u")//Predicate
select n);
//lazy loading of the linq query is actually a benefit
//unless we loop around to yeild the result we are not loading the memory here
foreach (var item in result)
{
Console.WriteLine(item);
}
Console.ReadLine();
//this loop can be better used by more concise lmabda expression
Array.ForEach <string>(result.ToArray <string>(), s => Console.WriteLine(s));
Console.ReadLine(); //it is the choice of the developer how he wants to write statements
// we want all the integers that are greater than 2
int[] numbers = new int[] { 1, 2, 3, 4, 5, 6, 7, 8 };
var numbersResult = from i in numbers
where i <= 2
select i;
Array.ForEach <int>(numbersResult.ToArray <int>(), n => Console.WriteLine(n));
Console.ReadLine();
//C# code > LINQ -> EF -> database
using (FoundationEntities db = new FoundationEntities())
{
var employeeResult = from c in db.Candidates
select c.Id;
Array.ForEach <string>(employeeResult.ToArray <string>(), e => Console.WriteLine(e));
Console.ReadLine();
}
Student[] students = new Student[] {
new Student()
{
Age = 22, Name = "A", Contacts = new List <Contact>()
},
new Student()
{
Age = 24, Name = "B", Contacts = new List <Contact>()
},
new Student()
{
Age = 31, Name = "C", Contacts = new List <Contact>()
},
new Student()
{
Age = 15, Name = "D", Contacts = new List <Contact>()
},
new Student()
{
Age = 34, Name = "F", Contacts = new List <Contact>()
},
new Student()
{
Age = 26, Name = "G", Contacts = new List <Contact>()
},
new Student()
{
Age = 22, Name = "H", Contacts = new List <Contact>()
},
new Student()
{
Age = 22, Name = "I", Contacts = new List <Contact>()
},
new Student()
{
Age = 22, Name = "J", Contacts = new List <Contact>()
},
};
//using the mathematics operator and the annonymous projection
var studentResult = from s in students
where s.Age > 22
select new { Alias = s.Name };
Array.ForEach(studentResult.ToArray(), s => Console.WriteLine(s.Alias));
Console.ReadLine();
//we can also use the predicate and call the custom function in place of the simple where statements.
Predicate <Student> predic = IsValidPerson;
var resultUsingPredicate = (from s in students
select s).Where(s => predic.Invoke(s));
Array.ForEach <Student>(resultUsingPredicate.ToArray <Student>(), s => Console.WriteLine(s.Name));
Console.ReadLine();
//cascaded objects
var contacts = from s in students
select s.Contacts; //this statement would not work
//shape of contacts is -- IEnumerable<IEnumerable<Contact>>
var contactsFlat = students.SelectMany(s => s.Contacts);
// shape of left side would be -- Ienumerable<Contact>
Array.ForEach <Contact>(contactsFlat.ToArray <Contact>(), c => Console.WriteLine(c));
Console.ReadLine();
string[] studentNames = new string[] { "Niranjan", "Guru", "Arun", "Niranjan", "Arun" };
string[] tutors = new string[] { "Niranjan", "victor", "Shiva" };
//Arun Arun Guru Guru Niranjan Niranjan
//Comment from codechira
// ....
//Pagination and skipping results from the top
var myResult = (from n in names
orderby n //this statement is vital when it comes to skipping. If missing the entire thing will not work
select n).Distinct <string>().Skip <string>(1).Take <string>(2);
Array.ForEach <string>(myResult.ToArray <string>(), r => Console.WriteLine(r));
Console.ReadLine();
//Working with inner joins
//Niranjan : Niranjan
//Niranjan :victor
//Niranjan: Shiva
//Guru: Niranjan
//Guru: Victor
//Guru: shiva ..
var innerJoin = from n in names
join t in tutors on n equals t
select n;
Array.ForEach <string>(innerJoin.ToArray <string>(), i => Console.WriteLine(i));
Console.ReadLine();
var orderedNames = from n in names
orderby n
select n;
//this is a an regular means of doing things
foreach (var item in orderedNames)
{
Console.WriteLine(item);
}
Console.ReadLine();
//but here is a whacky way of doing this.
Array.ForEach <string>(orderedNames.ToArray <string>(), n => Console.Writeline(n));
Console.ReadLine();
int[] anotherNumberSet = new int[] { 1, 2, 3, 4, 5, 6, 7, 8 };
var orderedResult = from i in numbers
where i > 2
orderby i descending
select i;
foreach (var item in orderedResult)
{
Console.WriteLine(item);
}
Console.ReadLine();
}
