Question

Is is better to do a joined query like this:

var employer = (from person in db.People                   join employer in db.Employers                   on person.EmployerID equals employer.EmployerID                    where person.PersonID == idPerson                   select employer).FirstOrDefault(); 

Or is it just as good to do the easy thing and do this (with null checks):

var employer = (from person in db.People                   where person.PersonID == idPerson                   select person).FirstOrDefault().Employer; 

Obviously, in this one I would actually have to do it in 2 statements to get in the null check.

Is there any sort of best practice here for either readability or performance issues?

Answer 1

I’d use this:

var employer = (from person in db.People                 where person.PersonID == idPerson                 select person.Employer).FirstOrDefault(); 

It’s got the simplicity of the first version but still only fetches the data for the employer (rather than the person and the employer).