Christian Buettner-167247 (2/18/2010)
Sorry, but option 1 is still wrong.Exclusive locks prevent access to a resource by concurrent transactions
Read access is not prevented in case of NOLOCK or READ UNCOMMITTED
Exactly. Another option is 'ALTER DATABASE xxx SET READ_COMMITTED_SNAPSHOT ON'. This, unlike NOLOCK, does not violate one of the ACID principles (isolation).
I am also puzzled with the fourth answer:
Data modification statements typically request both shared locks and exclusive locks
The word 'typically' is so vague. For example, typically I work with databases with the READ_COMMITTED_SNAPSHOT option turned on. Data modification statements typically don't request shared locks in this case. So I didn't select the fourth answer.