You have designed the database for a web site that is used to purchase concert tickets. During a ticket purchase, a buyer views a list of available tickets, decides whether to buy the tickets, and then attempts to purchase the tickets. This list of available tickets is retrieved in a cursor. For popular concerts, thousands of buyers might attempt to purchase tickets at the same time. Because of the potentially high number of buyers at any one time, you must allow the highest possible level of concurrent access to the data. How should you design the cursor?

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You have designed the database for a web site that is used to purchase concert tickets. During a ticket purchase, a buyer views a list of available tickets, decides whether to buy the tickets, and then attempts to purchase the tickets.
This list of available tickets is retrieved in a cursor. For popular concerts, thousands of buyers might attempt to purchase tickets at the same time.
Because of the potentially high number of buyers at any one time, you must allow the highest possible level of concurrent access to the data.
How should you design the cursor?

Create a cursor within an explicit transaction, and set the transaction isolation level to REPEATABLE READ.

Create a cursor that uses optimistic concurrency and positioned updates. In the cursor, place the positioned UPDATE statements within an explicit transaction.

Create a cursor that uses optimistic concurrency. In the cursor, use UPDATE statements that specify the key value of the row to be updated in the WHERE clause, and place the UPDATE statements within an implicit transaction.

Create a cursor that uses positioned updates. Include the SCROLL_LOCKS argument in the cursor definition to enforce pessimistic concurrency. In the cursor, place the positioned UPDATE statements within an implicit transaction.

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