c# - Lambda Expression for join -

public class coursedetail     {         public coursedetail();         public string courseid { get; set; }         public string coursedescription { get; set; }         public long courseser { get; set; }     }   public class refuidbycourse     {         public long courseser {  get;  set; }         public double delivereddose{ get; set; }         public double planneddose{ get; set; }         public string refuid {  get;  set; }      }  public class refdata     {        public double dailydoselimit {  get;  set; }        public string refname {  get;  set; }        public string refuid {  get;  set; }        public double sessiondoselimit {  get;  set; }     }  public class coursesummary       {               public long courseser { get; set; }            public double delivereddose{ get; set; }            public double planneddose{ get; set; }            public list<refdata> lstrefdata {get;set;}      } 

for 1 courseser there can multiple refuid in refuidbycourse , every refuid there 1 record in refdata

i have list of coursedetail,refuidbycourse , refdata courseser exist in coursedetail have create list of coursesummary.

one thing can do loop coursedetail , fetch respective refdata using linq query , create object of coursesummary , add in list.

but there way 1 linq query instead of doing loop through

the lambda join bit involved - here's simple example:

list<person> people = new list<person>(); list<persontype> peopletypes = new list<persontype>();  var joined = people.join(peopletypes,    peoplekey => peoplekey.persontype,    peopletypeskey => peopletypeskey.typeid,    (person, personetype) => new      {        name = person.name,        typeid = personetype.typeid      }); 

i find query syntax lot more readable lambdas joining

        var joined2 = p in people                       join ptype in peopletypes                       on p.persontype equals ptype.typeid                       p.name.startswith("whatever")                       select new { name = p.name, typeid = ptype.typeid };