How you have ur mappings setup is kinda crucial.
If you want the employee always loaded with the committee (i.e. -
every time you session.load<committee>(id), you want the query to be a
join), then you need to have in the committee mapping constructor:
base.references<employee>(x=>x.Employee)
.keycolumn("empidcolname")
.fetch.join();
I'm not exactly sure on that syntax (specifically the .references &
keycolumn. It might be association & foreignkey?) .. But that should
be pretty close.
You probably don't want the employee having a bi-directional reference
back to the committe (for employee re-use in other associations.
depends on ur model tho. It could lead to some nasty n+1 sql if
committee has other collections,dependencies), so u wont need an
association/reference in the employee.
On 9/29/11, Influently NHiberater <[email protected]> wrote:
> How does an ORM framework handle joins like what we do in plain SQL? Is it
> the case that an ORM framework doesn't explicitly join two or more tables?
>
> Suppose I have the following two tables in my database:
>
> Employees
> {
> Eid int primary key,
> FirstName varchar(20),
> LastName varchar(20)
> }
>
> Committees
> {
> Cid int primary key,
> Name varchar(50), <--- This is the committee name.
> ChairId int references Employees.Eid
> }
>
> And I have my POCO classes, EmployeeMap and CommitteeMap defined.
>
> Now how can I use Linq or FluentNHibernate Linq to get something like what
> the following SQL query would give me?
>
> SELECT e.FirstName, e.LastName, c.Name
> FROM Employees e
> INNER JOIN Committees c
> ON e.Eid = c.ChairId
>
> All FluentNHibernate examples I've seen online query only one table, and
> which is pretty simple and straightforward, but in reality, we rarely query
> only one table.
>
> Can anyone give me a working example or a pointer to such a thing? Thank
> you.
>
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