Managing Multiuser Databases(Engineering > Computer Science And Engineering > Database System ) Questions and Answers

Question 1. Locks placed by command are called ________ .
  1.    shared locks
  2.    exclusive locks
  3.    explicit locks
  4.    implicit locks
Explanation:-
Answer: Option C. -> explicit locks
Question 2. In this instance, dirty reads are disallowed, while nonrepeatable reads and phantom reads are allowed.
  1.    Read uncommitted
  2.    Repeatable read
  3.    Read committed
  4.    Serializable
Explanation:-
Answer: Option C. -> Read committed
Question 3. Which of the following locks the item from change but not from read?
  1.    Explicit lock
  2.    Exclusive lock
  3.    Shared lock
  4.    Implicit lock
Explanation:-
Answer: Option C. -> Shared lock
Question 4. A transaction for which all committed changes are permanent is called:
  1.    consistent.
  2.    durable.
  3.    isolated.
  4.    atomic.
Explanation:-
Answer: Option B. -> durable.
Question 5. Which of the following occurs when a transaction rereads data and finds new rows that were inserted by a command transaction since the prior read?
  1.    Dirty read
  2.    Phantom read
  3.    Consistent read
  4.    Nonrepeatable read
Explanation:-
Answer: Option B. -> Phantom read
Question 6. Which of the following occurs when a transaction rereads data it has previously read and finds modification or deletions caused by a committed transaction?
  1.    Nonrepeatable read
  2.    Dirty read
  3.    Phantom read
  4.    Consistent read
Explanation:-
Answer: Option A. -> Nonrepeatable read
Question 7. Which of the following refers to a cursor type where changes of any type and from any source are visible?
  1.    Dynamic
  2.    Forward only
  3.    Keyset
  4.    Static
Explanation:-
Answer: Option A. -> Dynamic
Question 8. The advantage of optimistic locking is that:
  1.    the lock never needs to be obtained.
  2.    the lock is obtained before the transaction has processed.
  3.    the lock is obtained only after the transaction has processed.
  4.    transactions that are best suited are those with a lot of activity.
Explanation:-
Answer: Option C. -> the lock is obtained only after the transaction has processed.
Question 9. Which of the following disallows both dirty reads and nonrepeatable reads, but allows phantom reads?
  1.    Serializable
  2.    Repeatable read
  3.    Read uncommitted
  4.    Read committed
Explanation:-
Answer: Option B. -> Repeatable read
Question 10. Which of the following refers to a cursor type that when the cursor is opened, a primary key value is saved for each row in the recordset; when the application accesses a row, the key is used to fetch the current values of the row?
  1.    Keyset
  2.    Static
  3.    Dynamic
  4.    Forward only
Explanation:-
Answer: Option A. -> Keyset
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