c# - How to update a record by id? -


i new entityframework , having trouble understand why first code doesn't update second does. aim update record without querying db.

is obvious?

using (chatdbentities db = new chatdbentities())     {         // update buddy         onlines buddy = new onlines();         buddy.id = 56;         buddy.last_seen = datetime.now;         buddy.status = (int)userstatuses.status.chatting;         buddy.connected_to_id = 34;         buddy.room_id = 2;          db.savechanges();      }      using (chatdbentities db = new chatdbentities())     {         // update buddy         var buddy = db.onlines.first();         buddy.last_seen = datetime.now;         buddy.status = (int)userstatuses.status.chatting;         buddy.connected_to_id = 34;         buddy.room_id = 2;          db.savechanges();      }

it looks related "id" primary identity key.

you have retrieve entity in order update it, can't create new 1 same id record database , expect ef magically know needs update database. try attaching objectcontext not how supposed updates.


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