Are SQL Server 2000+ transactions connection dependent?

Question

Case 1:

1. I start a connection to the DB
2. I BEGIN a TRANSACTION

3. I close the connection

   What happens to the transaction?

Case 2:

1. I start a connection to the DB
2. I BEGIN a TRANSACTION
3. I start a concurrent connection to the same DB
4. With the second connection I modify the contents of a table

5. With the first connection I ROLLBACK the TRANSACTION

   What happens to the modifications?

Answer 1

Case 1: roll back

Case 2: at step 4, you can't modify rows which are touched by the first connection so there's no effect: the second connection can't modify, it will wait (due to the locks).

Answer 2

Just to add: Transactions are session dependent - this explains your first question.