Entity Framework query - return unique rows from child table

问题

I have Entity Framework model as below and data in the corresponding database tables:

Question: How do I query the model for returning all the rows (full entities, not anonymous type) from sales_type relevant to a given person ?

If the data is as above, then for John, the query should return first three rows from sales_type-table and for Mark it should return the rows 2 and 5.

回答1:

Something like this

ctx.PersonSales
   .Where(ps=> ps.Person.Id = myPersonId)
   .Where(ps=> ps.SalesMapping != null && ps.SalesMapping.SalesType != null)
   .Select(ps=>ps.SalesMapping.SalesType)
   .Distinct();

回答2:

Maybe something like this:

var personId=1;
var result= (
        from salesType in db.sales_type
        where
            (
                from salesMapping in db.sales_mapping
                join personSale in db.person_Sales
                    on salesMapping.id equals personSale.sales_mapping_id
                join person in db.person
                    on personSale.person_id equals person.id
                where
                    person.Id == personId
                select salesMapping.sales_type_id
            ).Contains(salesType.id)
        select salesType
    ).ToList();

Where db is the linq data context

来源：https://stackoverflow.com/questions/21877293/entity-framework-query-return-unique-rows-from-child-table