Exam 70-762 topic 1 question 120 discussion

HOW about "E" -> enable snapshot; no dirty reads, etc. ?

Just because you change Snapshot isolation to on does not mean it is being utilized. So "E" would only use more resources, but not prevent the locking. https://www.brentozar.com/archive/2013/01/implementing-snapshot-or-read-committed-snapshot-isolation-in-sql-server-a-guide/

The table name is Projections, meaning not required high degree of accuracy NOLOCK is OK The answer is correct

The NOLOCK and READUNCOMMITED hints are only allowed with SELECT statements. If we try to use this for an UPDATE, DELETE or INSERT we will get an error.

Use the NOLOCK query hint if one of the transactions is a SELECT statement, but only use this method if the trade-off of a deadlock for dirty reads is acceptable. The use of the NOLOCK table hint is common in reporting applications against OLTP systems in which lack of consistency is a trade-off for faster query performance. However, when users are dissatisfied with inconsistent results, you can recommend removing this table hint and allow the default isolation in SQL Server to manage transaction isolation. Long write operations can block the report from executing. Similarly, if the report takes a long time to execute, the read operation can block write operations. Exclusive (X) This lock mode protects a resource during INSERT, UPDATE, or DELETE operations to prevent that resource from multiple concurrent changes. While the lock is held, no other transaction can read or modify the data, unless a statement uses the NOLOCK hint or a transaction runs under the read uncommitted isolation level. Rather than change the isolation level at the session level, you can force the read uncommitted isolation level by using the NOLOCK hint.