C# LINQ Basics

using System.Linq; # import LINQ
var result = from num in numbers # iterate collection
              where num > 5 # filter condition
              select num; # select elements

var result = numbers.Where(n => n > 5); # filter
var mapped = numbers.Select(n => n * 2); # transform
var first = numbers.First(); # get first element
var single = numbers.FirstOrDefault(); # first or null

numbers.Where(n => n > 10) # filter by condition
numbers.Take(5) # take first 5
numbers.Skip(3) # skip first 3
numbers.Distinct() # remove duplicates

numbers.Count() # count elements
numbers.Sum() # sum all elements
numbers.Average() # calculate average
numbers.Min() # find minimum
numbers.Max() # find maximum

numbers.OrderBy(n => n) # sort ascending
numbers.OrderByDescending(n => n) # sort descending
people.OrderBy(p => p.Name).ThenBy(p => p.Age) # sort by multiple