SELECT Kids FROM Reservations WHERE CheckIn  =  "2010-09-21" AND FirstName  =  "DAMIEN" AND LastName  =  "TRACHSEL";
How many kids stay in the room DAMIEN TRACHSEL checked in on Sep 21, 2010?
[Schema (values) (types)]: | inn_1 |  Rooms : roomid (text) , roomname (text) , beds (text) , bedtype (number) , maxoccupancy (text) , baseprice (number) , decor (number) | Reservations : code (text) , room (text) , checkin (text) , checkout (number) , rate (text) , lastname (number) , firstname (number) , adults (text) , kids (number);