Is it possible to execute an efficient multiple row DELETE or UPDATE using EF4?

问题

I'm a developer still learning the intricacies of EF4. I am well aware of how to pull down a list of objects and iterate through deleting them in a loop but I can't bring myself to write code that will execute n statements (and database round-trips) for n records when doing a mass update or delete.

A classic case for this is deleting child records prior to deleting a related parent record to maintain referential integrity... (yes, I employ soft deletes by default but humor me)

In a stored procedure I'd just execute the SQL, like so:

DELETE FROM someChildTable WHERE ForeignTableId = @keyToGo
DELETE FROM parentTable WHERE Id = @keyToGo

In Linq To SQL I would do this:

dataContext.ChildrenTable.DeleteAllOnSubmit(from c in dataContext.ChildrenTable
                                            where c.ParentTableId == keyToGo
                                            select c);
dataContext.ParentTable.DeleteOnSubmit(parentToGo);
dataContext.SubmitChanges();

In NHibernate I would do this:

nhSession.CreateQuery("delete from ChildrenTable where ParentTable.Id = :keyToGo")
                        .SetInt32("keyToGo", keyToGo)
                        .ExecuteUpdate();
nhSession.Delete(parentToGo);

I've looked for the EF equivalent for any of these without success. Must I really drop back to a stored procedure to do this within the context of EF4? I hope not; please share.

回答1:

EF is an ORM - object-relational mapper. It's great at mapping rows and columns from your relational database into your .NET object model - and this works best for reading, inserting, updating one or a few objects.

EF is not designed and intended as a tool to handle large operations, it's not designed and optimized to do batch updates, batch deletes etc. Those are handled much better by either using straight ADO.NET to execute those T-SQL commands against the database, or by just calling a stored procedure to do the work.

So in this situation, I would probably create a stored procedure to handle the delete operation, and then import that stored proc into my EF model so I can call it like a method on my EntityContext and let SQL Server do the heavy lifting.

回答2:

If you make the relationship between the parent object and child object to be "Cascade all" in the database all you need to do from EF is to delete the parent object. The child objects (now called orphans) will be deleted by the database for you. There is no other way to do this efficiently in EF at the moment.

回答3:

If you don't want to use the Cascade All as has been suggested then check out the ObjectContext.ExecuteStoreCommand function which allows to run ad-hoc queries against the data store. This will most likely be the most efficient way to perform a bulk delete or update.

来源：https://stackoverflow.com/questions/4320773/is-it-possible-to-execute-an-efficient-multiple-row-delete-or-update-using-ef4