在实体框架6中更新，无需往返

In EF 4.1, when I wanted to update a record, I could avoid the roundtrip of loading it first by creating a new entity, setting the primary key, attaching it to the DBContext, then updating the field. Change tracking would ensure that only the fields I changed after attaching the entity would update. This method is explained In EF 4.1, when I wanted to update a record, I