Exam 70-762 topic 1 question 103 discussion

HOTSPOT -
You are developing queries and stored procedures to support a line-of-business application.
You need to use the appropriate isolation level based on the scenario.
Which isolation levels should you implement? To answer, select the appropriate isolation level for each scenario in the answer area. Each isolation level may be used only one.
NOTE: Each correct selection is worth one point.
Hot Area:

Suggested Answer:
Box 1: READ UNCOMMITTED -
Transactions running at the READ UNCOMMITTED level do not issue shared locks to prevent other transactions from modifying data read by the current transaction. READ UNCOMMITTED transactions are also not blocked by exclusive locks that would prevent the current transaction from reading rows that have been modified but not committed by other transactions. When this option is set, it is possible to read uncommitted modifications, which are called dirty reads.
Values in the data can be changed and rows can appear or disappear in the data set before the end of the transaction.

Box 2: READ COMMITTED -
READ COMMITTED specifies that statements cannot read data that has been modified but not committed by other transactions.
SERIALIZABLE specifies that statements cannot read data that has been modified but not yet committed by other transactions.

Box 3: REPEATABLE READ -
REPEATABLE READ specifies that statements cannot read data that has been modified but not yet committed by other transactions and that no other transactions can modify data that has been read by the current transaction until the current transaction completes.

Box 4: SNAPSHOT -
If READ_COMMITTED_SNAPSHOT is set to ON, the Database Engine uses row versioning to present each statement with a transactionally consistent snapshot of the data as it existed at the start of the statement.
References:
https://docs.microsoft.com/en-us/sql/t-sql/statements/set-transaction-isolation-level-transact-sql?view=sql-server-2017