If insert statement was within Explicit transaction then even first row will not be inserted and the result of final query will be 0. Am I right?
Yes (assuming you start the transaction after the table creation and before the first insert). The ROLLBACK TRAN in the trigger will rollback the active transaction. In the code as posted, each INSERT starts its own implicit transaction which is committed (or rolled back) at the end of the statement. If you explicitly start a transaction before the first insert, then no implicit transactions will be started. And the ROLLBACK TRAN in the trigger will roll back that explicit transaction.
Whether XACT_ABORT can play any role here?
No. XACT_ABORT has an effect on errors that do not normally cause a rollback in an explicit transaction. In the code as posted, there is no explicit transation, so that alone means that XACT_ABORT has no effect. Adding an explicit transaction doesn't change that, as the error in this code already causes a rollback - so there is nothing for XACT_ABORT to do that the trigger code doesn't already do.
By the way, it's very easy to check this kind of questions for yourself. Just copy the code in SSMS, make changes, and see what happens. (Don't do this on a production database, or even on a production instance!)
Hugo Kornelis, SQL Server/Data Platform MVP (2006-2016)
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