Question

I want to update the only field of entity when I know entity Id.

Is it possible in LINQ to SQL without retrieving full entity (with all fields from DataContext that is overhead) ? Is it possible to create and attach entity to DataContext and mark the exact field(s) to synchronize on DataContext.SubmitChanges (or something like that)?

Thank you in advance!

Answer 1

Yes you can:

Foo foo=new Foo { FooId=fooId }; // create obj and set keys
context.Foos.Attach(foo);
foo.Name="test";
context.SubmitChanges();

In your Dbml set UpdateCheck=”Never” for all properties.

This will generate a single update statement without a select.

One caveat: if you want to be able to set Name to null you would have to initialize your foo object to a different value so Linq can detect the change:

Foo foo=new Foo { FooId=fooId, Name="###" };
...
foo.Name=null;

If you want to check for a timestamp while updating you can do this as well:

Foo foo=new Foo { FooId=fooId, Modified=... }; 
// Modified needs to be set to UpdateCheck="Always" in the dbml