在哪里加入。 哪个更好用

Question

Currently I'm running some code and got some question about this. Below are the code listings of two LINQ to Entites queries.

Code listing A:

IQueryable list = 
    from tableProject in db.Project 
    select new {StaffInCharge = (
        from tableStaff in db.Staff
        where tableStaff.StaffId == tableProject.StaffInChargeId 
        select tableStaff.StaffName)};

Code listing B:

IQueryable list = 
    from tableProjectin db.Project 
    join tableStaff in db.Staff
        on tableProject.StaffInChargeId
        equal tableStaff.StaffId
    select new {StaffInCharge = tableStaff.StaffName};

What I want to figure out is which one will be better and faster if I have to select many column from many others table.

Thanks.

Answer 1

this is the comment from @Tim Schmelter

"The article(actually my SO-Question) relates to LINQ-To-DataSet what is based on LINQ-To-Objects. Linq to SQL or Linq to Entities might be optimized by the DBMS in that way that a where clause has the same performance as a join."

and the link is Why is LINQ JOIN so much faster than linking with WHERE? i think it is very useful.