Per Paul Randal in https://www.sqlskills.com/blogs/paul/a-sql-server-dba-myth-a-day-2630-nested-transactions-are-real/
The commit of a nested transaction has absolutely no effect – as the only transaction that really exists as far as SQL Server is concerned is the outer one. Can you say ‘uncontrolled transaction log growth’? Nested transactions are a common cause of transaction log growth problems because the developer thinks that all the work is being done in the inner transactions so there’s no problem.
The rollback of a nested transaction rolls back the entire set of transactions – as there is no such thing as a nested transaction.
Your developers should not use nested transactions. They are evil.
Against stupidity the gods themselves contend in vain. -- Friedrich Schiller
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