Question

Is there an equivalent of a SQL IN statement in LINQ to objects?

Answer 1

Yes – Contains.

var desiredNames = new[] { 'Jon', 'Marc' };  var people = new[] {     new { FirstName='Jon', Surname='Skeet' },     new { FirstName='Marc', Surname='Gravell' },     new { FirstName='Jeff', Surname='Atwood' } };  var matches = people.Where(person => desiredNames.Contains(person.FirstName));  foreach (var person in matches) {     Console.WriteLine(person); } 

(In LINQ to SQL this ends up as an ‘IN’ query.)

Note that in LINQ to Objects the above isn’t really very efficient. You’d be better off with a join:

var matches = from person in people               join name in desiredNames on person.FirstName equals name               select person; 

(This could still be done with dot notation of course, but it ends up being somewhat messier.)