private static void Where_Basic()
{
foreach (Person p in PersonsDatabase.AllPersons())
{
p.Print();
}
Console.WriteLine("-----------------------------------------------------");
Console.WriteLine("Persons over 14 years with full name starting with 'M'");
Console.WriteLine("-----------------------------------------------------");
var query = PersonsDatabase.AllPersons()
.Where(p => (p.Age >= 14) &&
p.FullName.StartsWith("M"));
// Or:
//var query = from p in PersonsDatabase.AllPersons()
// where (p.Age >= 14) && p.FullName.StartsWith("M")
// select p;
foreach (Person p in query)
{
p.Print();
}
}
private static void GroupBy_Basic()
{
var query = from p in PersonsDatabase.AllPersons()
where p.Age > 30
orderby p.DateOfBirth.Year ascending
group p by p.DateOfBirth.Year into yearsGroups
where (yearsGroups.Key >= 1950) && (yearsGroups.Key <= 1970)
select yearsGroups;
//var query = PersonsDatabase.AllPersons()
// .Where(p => p.Age > 30)
// .OrderBy(p => p.DateOfBirth.Year)
// .GroupBy(p => p.Age);
foreach (var group in query)
{
Console.WriteLine("--------------");
Console.WriteLine($"Persons born in year: {group.Key}");
Console.WriteLine("--------------");
foreach (var p in group)
{
p.Print();
}
}
}
private static void Select_Basic_And_With_Index()
{
var query = PersonsDatabase.AllPersons()
.Select((p, index) => new { Name = p.FullName, Index = index });
//IEnumerable<string> query = from p in PersonsDatabase.AllPersons()
// select p.FullName;
foreach (var personNameAndIndex in query)
{
Console.WriteLine($"{personNameAndIndex.Index}) {personNameAndIndex.Name}");
}
}
private static void OrderBy_Basic()
{
//var query = PersonsDatabase.AllPersons()
// .Where(p => (p.Age > 20) && (p.Age < 40))
// .OrderBy(p => p.Age)
// .ThenByDescending(p => p.FullName);
var query = from p in PersonsDatabase.AllPersons()
where (p.Age > 20) && (p.Age < 40)
orderby p.Age ascending, p.FullName descending
select p;
foreach (Person p in query)
{
p.Print();
}
}
private static void Where_With_Index()
{
int index = 0;
foreach (Person p in PersonsDatabase.AllPersons())
{
p.Print(index);
index++;
}
Console.WriteLine("-----------------------------------------------------");
Console.WriteLine("Persons over 14 years with full name starting with 'M'");
Console.WriteLine("-----------------------------------------------------");
var query1 = PersonsDatabase.AllPersons()
.Where(p => (p.Age >= 14) &&
p.FullName.StartsWith("M"));
//var query1 = from p in PersonsDatabase.AllPersons()
// where (p.Age >= 14) && p.FullName.StartsWith("M")
// select p;
index = 0;
foreach (Person p in query1)
{
p.Print(index);
index++;
}
Console.WriteLine("-----------------------------------------------------");
Console.WriteLine("Persons over 14 years with full name starting with 'M' and on even index");
Console.WriteLine("-----------------------------------------------------");
var query2 = query1.Where((p, index) => index % 2 == 0);
foreach (Person p in query2)
{
p.Print();
}
}
