Nested Transaction - Microsoft SQL Server (MSSQL)

 SP - @@TxnCount
Use Try Catch Block SQL 
Rollback - Sets  @@TRANCOUNT to 0
Commit - decrements   @@TRANCOUNT Counter by 1

When Counter becomes Zero, Commit or Rollback actually does take its effect
Actually, No Nested Txn in MSSQL
Only 1 Txn in MSSQL

https://sqlinthewild.co.za/index.php/2015/11/03/a-mess-of-nested-transactions/

OUTPUT Clause (Transact-SQL)

https://docs.microsoft.com/en-us/sql/t-sql/queries/output-clause-transact-sql?view=sql-server-ver15