Sugar
Butter

 IEnumerable<Ingredient> query = ingredients.Where((ingredient, index) => ingredient.Name == "Sugar" || index == 4);

 IEnumerable<Ingredient> gueryExpression =
from i in ingredients
where i.Calories >= 200
select i;

 IEnumerable<string> query = ingredients.Select(x => x.Name);

 IEnumerable<int> query = ingredients.Select(x => x.Name.Length);

{ Name = Sugar, Length = 5 }
{ Name = Egg, Length = 3 }
{ Name = Milk, Length = 4 }
{ Name = Flour, Length = 5 }
{ Name = Butter, Length = 6 }

 S
u
g
a
r
E
g
g
M
i
l
k
F
l
o
u
r
B
u
t
t
e
r

 Sugar
Egg
Milk

Sugar
Milk

 IEnumerable<Ingredient> query =
(from i in ingredients
  where i.Calories > 100
  select i).Take(2);
TakeWhile

 Sugar
Egg
Milk

 Flour
Butter

 First Page :
 - Sugar
 - Egg
Second Page :
 - Milk
 - Flour
Third Page :
 - Butter
SkipWhile

 Milk
Flour
Butter

 SELECT * FROM Table1
  WHERE (ABS(CAST(
  (BINARY_CHECKSUM(*) *
  RAND()) as int)) % 100) < 10

using System;
using System.Linq;
using Raven.Client.Document;
using RavenDBSample01.Models;

namespace RavenDBSample01
{
    class Program
    {
        static void Main(string[] args)
        {
            using (var store = new DocumentStore
            {
                Url = "http://localhost:8080"
            }.Initialize())
            {
                using (var session = store.OpenSession())
                {
                    var questions = session.Query<Question>().Where(x => x.Title.StartsWith("Raven"));
                    foreach (var question in questions)
                    {
                        Console.WriteLine(question.Title);
                    }
                }
            }
        }
    }
}

Available commands: cls, reset, gc, q
Request #   1: GET     -   179 ms - <system>   - 404 - /docs/Raven/Replication/Destinations
Request #   2: GET     - 3,818 ms - <system>   - 200 - /indexes/dynamic/Questions?&query=Title%3ARaven*&pageSize=128
        Query: Title:Raven*
        Time: 3,494 ms
        Index: Auto/Questions/ByTitle
        Results: 2 returned out of 2 total.

var questions = session.Query<Question>().Where(x => x.Title.StartsWith("Raven")).Take(128);

var questions = session.Advanced.LuceneQuery<Question>().Where("Title:Raven*").ToList();

var questions = session.Advanced.LuceneQuery<Question>().WhereStartsWith(x => x.Title, "Raven").ToList();

var query = session.Query<User>().Where(x => x.Name.StartsWith("A"));
var ageQuery = query.Where(x => x.Age > 21);
var eyeQuery = query.Where(x => x.EyeColor == "blue");

query - Name:A*
ageQuery - (Name:A*) AND (Age_Range:{Ix21 TO NULL})
eyeQuery - (Name:A*) AND (EyeColor:blue)

var luceneQuery = session.Advanced.LuceneQuery<User>().WhereStartsWith(x => x.Name, "A");
var ageLuceneQuery = luceneQuery.WhereGreaterThan(x => x.Age, 21);
var eyeLuceneQuery = luceneQuery.WhereEquals(x => x.EyeColor, "blue");

luceneQuery - Name:A* 
ageLuceneQuery - Name:A* Age_Range:{Ix21 TO NULL}
eyeLuceneQuery - Name:A* Age_Range:{Ix21 TO NULL} EyeColor:blue

session.Advanced.LuceneQuery<User>().UsingDefaultOperator(QueryOperator.And);

using System;
using System.Linq;
using Raven.Client.Document;
using RavenDBSample01.Models;

namespace RavenDBSample01
{
    class Program
    {
        static void Main(string[] args)
        {
            using (var store = new DocumentStore
            {
                Url = "http://localhost:8080"
            }.Initialize())
            {
                using (var session = store.OpenSession())
                {
                    int pageNumber = 0;
                    int resultsPerPage = 2;

                    var questions = session.Query<Question>()
                                           .Where(x => x.Title.StartsWith("Raven"))
                                           .Skip(pageNumber * resultsPerPage)
                                           .Take(resultsPerPage);
                    foreach (var question in questions)
                    {
                        Console.WriteLine(question.Title);
                    }
                }
            }
        }
    }
}

using System;
using System.Linq;
using Raven.Client.Document;
using RavenDBSample01.Models;
using Raven.Client;

namespace RavenDBSample01
{
    class Program
    {
        static void Main(string[] args)
        {
            using (var store = new DocumentStore
            {
                Url = "http://localhost:8080"
            }.Initialize())
            {
                using (var session = store.OpenSession())
                {
                    int pageNumber = 0;
                    int resultsPerPage = 2;
                    RavenQueryStatistics stats;
                    var questions = session.Query<Question>()
                                           .Statistics(out stats)
                                           .Where(x => x.Title.StartsWith("Raven"))
                                           .Skip(pageNumber * resultsPerPage)
                                           .Take(resultsPerPage);
                    foreach (var question in questions)
                    {
                        Console.WriteLine(question.Title);
                    }

                    Console.WriteLine("TotalResults: {0}", stats.TotalResults);
                }
            }
        }
    }
}

var list = session.Query<Question>().Where(q => q.By.In<string>(arrayOfUsers))).ToArray()

 SELECT * FROM tbl WHERE data IN (1, 2, 3)

public class Person
{
        public int Id { get; set; }                
        public string Name { get; set; }
        public int? Age { get; set; }
}

string name = null;
var list1 = ctx.Users.Where(x => x.Name == name).ToList();

SELECT
[Extent1].[Id] AS [Id],
[Extent1].[Name] AS [Name],
[Extent1].[Age] AS [Age]
FROM [dbo].[People] AS [Extent1]
WHERE [Extent1].[Name] = @p__linq__0
-- p__linq__0 (dbtype=String, size=-1, direction=Input) = null

 var list2 = ctx.Users.Where(x => !x.Age.HasValue).ToList();

int? age = null;
var list2 = ctx.Users.Where(x => object.Equals(x.Age, age)).ToList();

 var list1 = ctx.Users.Where(x => string.IsNullOrEmpty(x.Name)).ToList();

string name = null;
var list1 = ctx.Users.Where(x => name == null ? x.Name == null : x.Name == name).ToList();

 var list1 = ctx.Users.Where(x => x.Name == null).ToList();

public int CalculateElapsedDays(DateTime from)
{
   DateTime now = DateTime.Now;
   return (now - from).Days;
}

 public static int CalculateElapsedDays(DateTime from, DateTime now) => (now - from).Days;

public int Divide(int numerator, int denominator)
{
   return numerator / denominator;
}

var result = Divide(1,0);

public static int Divide(int numerator, NonZeroInt denominator)
{
   return numerator / denominator.Value;
}

Func<int, bool> isMod2 = x => x % 2 == 0;
var list = Enumerable.Range(1, 10);
var evenNumbers = list.Where(isMod2);

public static IEnumerable<T> Where<T>(this IEnumerable<T> ts, Func<T, bool> predicate)
{
   foreach (T t in ts)
      if (predicate(t))
         yield return t;
}