C# / Linq-to-sql - Lock datacontext.Table on insertonsubmit

Question

I'm currently creating a method on my data access class that is going to insert an entity object to the database and I was expecting to get the latest inserted ID afterwards... and I've already done that but then I was wondering what would happend if the method somehow gets invoked twice at the same time, would it return the wrong ID?

So as a work around to that I decided to Lock the table on my datacontext:

lock(dataContext.Persons)
{
    InsertOnSubmit(person);
    dataContext.SubmitChanges();
}

but I do feel like this is inappropriate... I mean, the table isnt big and it wont take long to the datacontext to submit changes... So my question is, what kind of trouble would I run into by locking it like that?

PS: Let me know if my question was not clear enough and I'll edit it!

Answer 1

There is no need to lock your table.

LINQ-to-SQL will automatically populate your ID field with the identity from the database upon your call to .SubmitChanges() when you insert your person .

The caveat is that both your database and L2S entity must define your ID field as an identity . On your Person entity, you should have that field defined as the primary key, IsDbGenerated=true , UpdateCheck=never , and have the correct database type.

Once you submit, you should be able to simply retrieve the ID from your Person entity:

dataContext.Persons.InsertOnSubmit(person);
dataContext.SubmitChanges();
var id = person.ID; // now has the database generated identity.

Answer 2

Im not sure if this is part of your concerns, but if you use TransactionScope you can pass in a TransactionOption that will deal with multiple transactions.

Check out TransactionOption.Isolationlevel